The argument rests on two main ingredients. First, the identification of Muhammad or "Islam" as the stone based on his discussion of Matthew 21:33-46 in section 6.13 which has already been proven wrong. Second, he claims that that Umar in the capture of Jerusalem fulfills the prophecy of Zechariah 9:9. [A claim that is repeated by Al-Kadhi at the end of chapter 10.]
Regarding this claim, we have two answers, a short one and a long one. The short is:
As we have observed so often with his claims, Mr. Al-Kadhi fails to give any evidence that Umar entered Jerusalem on a donkey. In fact, Muslim tradition speaks of either a horse or a white camel, but we could not find one reference that he rode in on a donkey.
This finishes the short argument.
Similar claim on this story were made in a newsgroup discussion: , , , 
The long answer is the below exposition of the true meaning of Zechariah's prophecy.
Zech 9:9-10 9 Rejoice greatly, O daughter of Zion; shout, O daughter of Jerusalem: behold, thy King cometh unto thee: he is just, and having salvation; lowly, and riding upon an ass, and upon a colt the foal of an ass. 10 And I will cut off the chariot from Ephraim, and the horse from Jerusalem, and the battle bow shall be cut off: and he shall speak peace unto the heathen: and his dominion shall be from sea even to sea, and from the river even to the ends of the earth.
In order to understand who these verses are speaking of, we need to look at more than just the two aspects that Al-Kadhi has mentioned. Zechariah defines more than just two characteristics of this person and it gives us clearer insight into the identity of the person and is in keeping with the context of the text. First this person is a King, he is also just, he has salvation, he is lowly, and he rides upon an ass, not just any ass, but a colt the foal of an ass, and last but not least, his dominion will be from sea to sea, even to the ends of the earth.
He is a King.
This person is not just any king, as the Scripture states "behold thy King" verse 9. Since the writing is to the "daughters of Zion, O daughters of Jerusalem" it is important to identify who these people are in order to have a clear understanding of who the King is. Ps 149:2 "Let Israel rejoice in him that made him: let the children of Zion be joyful in their King." Zeph 3:14 "Sing, O daughter of Zion; shout, O Israel; be glad and rejoice with all the heart, O daughter of Jerusalem."
It is clear that when Scripture uses the term "daughters of Zion", it is referring to Israel, the chosen people of God. This King is apparently the King of Israel. Not only is this a King of Israel, but if we back up to Zech 8:22-23 we find that it cannot be the king of a conquering nation as Al-Kadhi describes as having occurred in 638 CE, unless of course Al-Kadhi wants to say that the Muslim took hold of the skirt of the Jew and declared that "We will go with you: for we have heard that God is with you". (Zech 8:23)
Zech 8:22-23 22 Yea, many people and strong nations shall come to seek the LORD of hosts in Jerusalem, and to pray before the LORD. 23 Thus saith the LORD of hosts; In those days it shall come to pass, that ten men shall take hold out of all languages of the nations, even shall take hold of the skirt of him that is a Jew, saying, We will go with you: for we have heard that God is with you.
Ten men of different nations and languages shall take hold of the skirt of him that is a Jew, begging of him not to push them aside, but to take them along with him. This shows these people seeking out a Jew, as one of the chosen people of God. They seek to take hold of the skirt of his robe, to touch the hem of his garment, (Matt 14:36) saying, We will go with you, for we have heard that God is with you. If we are to remain in context of the verses found in these writings then not only does this person have to be a King, but he also has to be a Jew.
As we look at this King we see that it does not point us towards the second Muslim Caliph that conquered Israel in 638 CE. It points us to a Jew who is King. Matt. 1:1-17 shows the linage of Christ. Christ is a Jew and is also a King by birth, as also the wise men acknowledged in Matt 2:2 "Saying, Where is he that is born King of the Jews? for we have seen his star in the east, and are come to worship him."
He is just.
To further define who is being spoken of in Zech. 9:9 we should determine who the term just can be applied to, not simply one characteristic of the term, but rather who can fit all the characteristics of being just. In keeping with that thought, I have included the definition of just as given by Vines Expository Dictionary of Biblical Words.
JUST, JUSTLY 1. dikaios ^1342^ was first used of persons observant of dike, "custom, rule, right," especially in the fulfillment of duties towards gods and men, and of things that were in accordance with right. The Eng. word "righteous" was formerly spelt "rightwise," I. e., (in a) straight way. In the NT it denotes "righteous," a state of being right, or right conduct, judged whether by the divine standard, or according to human standards, of what is right. Said of God, it designates the perfect agreement between His nature and His acts (in which He is the standard for all men) (from Vine's Expository Dictionary of Biblical Words) (Copyright 1985, Thomas Nelson Publishers)
Can we say that Christ fulfilled His duties towards God and men, and demonstrate that He was in accordance with all that is right? While there may be many opinions in regard to that matter, the highest possible conformation would come from the Father himself. When Christ was baptized the Father spoke theses words; Matt 3:17 "And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased." At the mount of transfiguration the Father again spoke in regard to Jesus; Matt 17:5 "While he yet spake, behold, a bright cloud overshadowed them: and behold a voice out of the cloud, which said, This is my beloved Son, in whom I am well pleased; hear ye him." These were not words that Christ himself heard, but also others heard the testimony of the Father in regard to Christ; 2 Pet 1:17-18 "For he received from God the Father honour and glory, when there came such a voice to him from the excellent glory, This is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount."
As we continue on with the subject of being just, can we also show that Christ was proclaimed just by men? The wife of Pilate declared Christ a just man; Matt 27:19 "When he was set down on the judgment seat, his wife sent unto him, saying, Have thou nothing to do with that just man: for I have suffered many things this day in a dream because of him." Pilate declared that Christ was just, so much so that He washed his hand of innocent blood; Matt 27:24 "When Pilate saw that he could prevail nothing, but that rather a tumult was made, he took water, and washed his hands before the multitude, saying, I am innocent of the blood of this just person: see ye to it." The prophets of old declared the coming of the Just One; Acts 7:52 "Which of the prophets have not your fathers persecuted? and they have slain them which shewed before of the coming of the Just One; of whom ye have been now the betrayers and murderers:"
Not only do we have the testimony of both men and God in regard to Christ being just, but we can also see Christ being just by His actions. 1 Pet 3:18 For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit: Rev 15:3 And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints.
Was there justice in Umar?
From the "Hughes Dictionary of Islam, page 228, it says that "There were within the city 12,000 Greeks and 50,000 natives, and the Khalifah Umar insisted that all the Greeks depart within 3 days and that the natives should pay tribute. Where was the justice in expelling the citizens of Jerusalem?
He has salvation.
Salvation means to effect successfully the full delivery of someone or something from impending danger. The very word carries with it a twofold implication; (1) That someone or something needs to be saved and (2) That someone is able and willing to save. With these two points in mind lets look at each in order to identify who fits this definition of having salvation.
Someone or something needs to be saved.
In this case Zechariah is speaking of the need of Israel. Zech 8:13-15 And it shall come to pass, that as ye were a curse among the heathen, O house of Judah, and house of Israel; so will I save you, and ye shall be a blessing: fear not, but let your hands be strong. For thus saith the LORD of hosts; As I thought to punish you, when your fathers provoked me to wrath, saith the LORD of hosts, and I repented not: So again have I thought in these days to do well unto Jerusalem and to the house of Judah: fear ye not. We then find the reason that Israel is in trouble: Zech 1:4 Be ye not as your fathers, unto whom the former prophets have cried, saying, Thus saith the LORD of hosts; Turn ye now from your evil ways, and from your evil doings: but they did not hear, nor hearken unto me, saith the LORD.
The reason that Israel needs to be saved is not because of lack of wealth, or land, or the many other reasons that one might think. God says her problem is that she has turned from Him. Is that not the root cause of all the sorrow that we as men find ourselves in? From the very moment that Adam rebelled against God, he found himself faced with sorrow. Gen 3:17 "in sorrow shalt thou eat of it all the days of thy life;" And then David spoke in regard to his own sorrow in this manner; Ps 116:3-4 The sorrows of death compassed me, and the pains of hell gat hold upon me: I found trouble and sorrow. Then called I upon the name of the LORD; O LORD, I beseech thee, deliver my soul. It is apparent here in Zech as it is throughout the Scriptures that there is indeed a need for being saved.
From the Hadith of Bukhari, 5.41, it is shown that even upon his death, Umar feared meeting God. "By Allah! If (at all) I had gold equal to the earth, I would have ransomed myself with it from the Punishment of Allah before I meet Him". It does not seem that Umar had salvation, but rather found himself in the same boat as all mankind, in that he was a sinner in need of a savior.
Is there someone who is able and willing to save.
Someone who brings salvation must be able to fulfill two requirements, 1)He must be able to save. It is possible for a person to have the desire but not the ability to save another individual. Many a physician has stood in frustration beside the bed of his dying patient, wanting to give aid, but totally helpless to do so.
Now the question becomes is Jesus able? Jesus says that He is able, because He was anointed, and sent for that very purpose. Luke 4:18 "The Spirit of the Lord is upon me, because he hath anointed me to preach the gospel to the poor; he hath sent me to heal the brokenhearted, to preach deliverance to the captives, and recovering of sight to the blind, to set at liberty them that are bruised." It is not enough for someone to say they are able, many people claim to be able to do things, but lets look at the witness of others to confirm that it was not simply passing words that Christ spoke. Col 1:13-14 "Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son: In whom we have redemption through his blood, even the forgiveness of sins:" And again we see the first hand experience of others who were delivered; Luke 7:48-49 "And he said unto her, Thy sins are forgiven. And they that sat at meat with him began to say within themselves, Who is this that forgiveth sins also?"
Not only is He able to forgive sins, but He is able to heal; Matt 9:27-30 "And when Jesus departed thence, two blind men followed him, crying, and saying, Thou Son of David, have mercy on us. And when he was come into the house, the blind men came to him: and Jesus saith unto them, Believe ye that I am able to do this? They said unto him, Yea, Lord. Then touched he their eyes, saying, According to your faith be it unto you. And their eyes were opened; ...."
We can give countless examples of the ability of Christ, He forgave sin, He raised the dead, He healed, He was a great teacher, a prophet, and last but not least, He rose from the dead. No other comes close to the ability of Christ in all these areas. Some have possessed parts of those ability's for example Elijah the prophet was able to raise the dead (1 Kings 17:21-22), but never has any man been able to claim and show the ability that Christ had in every area. Rev 5:2-7 "And I saw a strong angel proclaiming with a loud voice, Who is worthy to open the book, and to loose the seals thereof? And no man in heaven, nor in earth, neither under the earth, was able to open the book, neither to look thereon. And I wept much, because no man was found worthy to open and to read the book, neither to look thereon. And one of the elders saith unto me, Weep not: behold, the Lion of the tribe of Juda, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof. And I beheld, and, lo, in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent forth into all the earth. And he came and took the book out of the right hand of him that sat upon the throne."
2) He must be willing to save. It is possible for a person to have the ability but not the desire to save another individual. In 1978 a man in desperate need of a rare blood transfusion died. He suffered and died needlessly, for one of his relatives possessed the rare type of blood and could have donated it to the dying man but refused to do so. (Some groups of people do not believe in blood transfusions).
Christ showed time after time that He was indeed willing. Matt 8:2-3 "And, behold, there came a leper and worshipped him, saying, Lord, if thou wilt, thou canst make me clean. And Jesus put forth his hand, and touched him, saying, I will; be thou clean. And immediately his leprosy was cleansed." The willingness of Christ was witnessed to; 1 Tim 2:3-4 "For this is good and acceptable in the sight of God our Saviour; Who will have all men to be saved, and to come unto the knowledge of the truth." 2 Pet 3:9 "The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance."
Jesus is the source, center, and sum total of salvation; Luke 1:68-69 "Blessed be the Lord God of Israel; for he hath visited and redeemed his people, And hath raised up an horn of salvation for us in the house of his servant David;" Luke 3:5-6 "Every valley shall be filled, and every mountain and hill shall be brought low; and the crooked shall be made straight, and the rough ways shall be made smooth; And all flesh shall see the salvation of God." Acts 4:10-12 "Be it known unto you all, and to all the people of Israel, that by the name of Jesus Christ of Nazareth, whom ye crucified, whom God raised from the dead, even by him doth this man stand here before you whole. This is the stone which was set at nought of you builders, which is become the head of the corner Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved."
He is lowly.
Phil 2:7-8 7 But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men: 8 And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.
"Made himself of no reputation" means to empty. The Greek word is Kenoo. Christ was 100% God when He was conceived by Mary, even at that time He could have spoken this world out of existence. John 1:1-4 "In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by him; and without him was not any thing made that was made. In him was life; and the life was the light of men." He did not empty himself of His deity, there was never a moment when He was not God. So the question becomes, "What did He empty himself of?".
He emptied Himself of the prerogatives of deity. He lived on this earth with certain limitations, but they where self limitations. Because He had laid aside His prerogatives of deity, He was willing to be born in a stable. He was willing to be an unknown carpenter. He could have had the shekinah glory with Him at all times, but He didn't. He was a human being, but He was God manifest in the flesh.
"He took upon Himself the form of a servant". Jesus came as a servant, He worked as a carpenter. He could have been born in the palace of Caesar, yet He came into this world as a working man. The prophet Isaiah said that Christ would come as a "root of Jesse" (Isaiah 11:10). Now we know that Jesus was of the line of David and thru that Jesus was rightfully the King, however Isaiah mentions David's father Jesse. Jesse was a farmer in Bethlehem, and the line of Christ was dropped back to the place of a peasant, a humble place. "He humbled himself". Many a man came up from a humble start in life and rises to lofty positions. That is a very common thing to do, however here we find that He left the lofty heights of heaven to become as man. He humbled himself. Does Christ show the attributes of being lowly as described by Zechariah? Yes in every way He was found to be both meek and lowly.
He rides in upon an ass
Matt 21:5-7 5 Tell ye the daughter of Sion, Behold, thy King cometh unto thee, meek, and sitting upon an ass, and a colt the foal of an ass. 6 And the disciples went, and did as Jesus commanded them, 7 And brought the ass, and the colt, and put on them their clothes, and they set him thereon.
Al-Kadhi says that Umar rode a donkey when he entered Jerusalem. What are his sources for saying this. According to Muir's "The Caliphate", page 146, Umar rode a horse when he entered Jerusalem. Here is the quote:
According to the Merriam Webster's Collegiate Dictionary, tenth edition, a palfrey is "a saddle horse other than a war horse, esp. a ladies light easy-gaited horse."
I have found no reference to Umar riding a donkey. I've found about 6 sources describing the event. Three say horse, three say camel, more or less. None say donkey. Here are the camel references:
The Rebuttal to "What Did Jesus Really Say?"
Answering Islam Home Page