Indeed, we can even find Jesus (pbuh) himself bearing witness in the Bible against the Jews that they had changed the commands and doctrines of God and substituted them with their own traditions. He says:
"Then came to Jesus scribes and Pharisees (learned Jews), which were of Jerusalem, saying, Why do thy disciples transgress the tradition of the elders? for they wash not their hands when they eat bread. But he answered and said unto them, Why do ye also transgress the commandment of God by your tradition? For God commanded, saying, Honour thy father and mother: and, He that curseth father or mother, let him die the death. But ye say, Whosoever shall say to [his] father or [his] mother, [It is] a gift, by whatsoever thou mightest be profited by me; And honour not his father or his mother, [he shall be free]. Thus have ye made the commandment of God of none effect by your tradition. [Ye] hypocrites, well did Esaias prophesy of you, saying, This people draweth nigh unto me with their mouth, and honoureth me with [their] lips; but their heart is far from me But in vain they do worship me, teaching [for] doctrines the commandments of men."
He also says: "Then spake Jesus to the multitude, and to his disciples, Saying, The scribes and the Pharisees sit in Moses' seat: All therefore whatsoever they bid you observe, [that] observe and do; but do not ye after their works: for they say, and do not. For they bind heavy burdens and grievous to be borne, and lay [them] on men's shoulders; but they [themselves] will not move them with one of their fingers. But all their works they do for to be seen of men: they make broad their phylacteries, and enlarge the borders of their garments. And love the uppermost rooms at feasts, and the chief seats in the synagogues, And greetings in the markets, and to be called of men, Rabbi, Rabbi But be not ye called Rabbi: for one is your Master, [even] Christ; and all ye are brethren. And call no [man] your father upon the earth: for one is your Father, which is in heaven. Neither be ye called masters: for one is your Master, [even] Christ. But he that is greatest among you shall be your servant. And whosoever shall exalt himself shall be abased; and he that shall humble himself shall be exalted. But woe unto you, scribes and Pharisees, hypocrites! for ye shut up the kingdom of heaven against men: for ye neither go in [yourselves], neither suffer ye them that are entering to go in. Woe unto you, scribes and Pharisees, hypocrites! for ye devour widows' houses, and for a pretence make long prayer: therefore ye shall receive the greater damnation. Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell than yourselves. Woe unto you, [ye] blind guides, which say, Whosoever shall swear by the temple, it is nothing; but whosoever shall swear by the gold of the temple, he is a debtor! [Ye] fools and blind: for whether is greater, the gold, or the temple that sanctifieth the gold? ... [Ye] fools and blind ... Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier [matters] of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone. [Ye] blind guides, which strain at a gnat, and swallow a camel. Woe unto you, scribes and Pharisees, hypocrites! for ye make clean the outside of the cup and of the platter, but within they are full of extortion and excess. [Thou] blind Pharisee, cleanse first that [which is] within the cup and platter, that the outside of them may be clean also. Woe unto you, scribes and Pharisees, hypocrites! for ye are like unto whited sepulchres, which indeed appear beautiful outward, but are within full of dead [men's] bones, and of all uncleanness. Even so ye also outwardly appear righteous unto men, but within ye are full of hypocrisy and iniquity. Woe unto you, scribes and Pharisees, hypocrites! because ye build the tombs of the prophets, and garnish the sepulchres of the righteous, And say, If we had been in the days of our fathers, we would not have been partakers with them in the blood of the prophets. Wherefore ye be witnesses unto yourselves, that ye are the children of them which killed the prophets. Fill ye up then the measure of your fathers. [Ye] serpents, [ye] generation of vipers, how can ye escape the damnation of hell?"
" (And remember) when the angels said: O Mary! Allah gives you glad tidings of a word from Him, whose name is the Messiah, Jesus, son of Mary, held in high honor in the world and the Hereafter, and of those brought near (unto Allah). He will speak unto mankind in his cradle and in his manhood, and he is of the righteous. She said: My Lord! How shall I have a son when no mortal has touched me? He said: So (it will be). Allah creates what He will. if He decrees a thing, He says unto it only: Be! and it is. And He will teach him the Scripture and wisdom, and the Torah and the Gospel. And will make him a messenger unto the children of Israel, (saying): I come unto you with a sign from your Lord, that I fashion for you out of clay the likeness of a bird, and I breathe into it and it is a bird, by Allah's leave. I heal him who was born blind, and the leper, and I raise the dead, by Allah's leave. And I announce unto you what you eat and what you store in your houses. Surely! therein is a sign for you, if you are believers. And (I come) confirming that which was before me of the Torah, and to make lawful some of that which was forbidden unto you. I come unto you with a sign from your Lord, so guard yourselves against Allah and obey me. Truely! Allah is my Lord and your Lord, so worship Him. That is a straight path. But when Jesus became conscious of their disbelief, he cried: Who will be my allies in the cause of Allah? The disciples said: We will be Allah's allies. We believe in Allah, and bear you witness that we have surrendered (unto Him). Our Lord! We believe in that which You have revealed and we follow him whom You have sent. So write us down among those who witness (to the truth). And they (the disbelievers) plotted, and Allah plotted (against them): and Allah is the best of plotters. When Allah said: 'O Jesus! I will take you and raise you to Myself and purify you of those who disbelieved, and I will make those who follow your above those who disbelieved till the Day of Resurrection, then unto Me is your return and I will judge between you in that in which you used to dispute. As for those who disbelieved, I shall punish them with a severe torment in this world and in the Hereafter, and they will have no champion [to save them]. And as for those who believed and did righteous deeds, Allah will pay them their reward in full. And Allah does not love the unjust. This is what We recite upon you of the verses and the Wise Reminder(the Qur'an). Verily the example of Jesus with Allah is as the example of Adam. He created him from dust then He said to him: 'Be!' and he was. This is the truth from your Lord, so be not of those who doubt. Then whosoever disputes with you after the knowledge has come unto you then say: Come, let us call our sons and your sons, and our women and your women, and ourselves and yourselves, then we will pray solemnly [to Allah]and invoke the curse of Allah upon those who lie. Verily, this is the true narrative, and there is no god but Allah. And indeed Allah is the All-Mighty the All-Wise. Then if they turn away then surely, Allah is All-Aware of the corrupters. Say O people of the Scripture, come unto a word that is just between us and you, that we worship none but Allah, and that we associate no partners with Him. And that none of us take each-other as lords besides Allah. But if they turn away then say: Bear you witness that we have submitted (We are Muslims!)." Aal-Umran(3):45-64.
There is much more which could be said about these matters, however, I will leave it up to the interested student to consult Prof. Friedman's book and make up their own minds. Fourteen hundred years ago, back when it was a blasphemy of the highest order punishable by death and worse to dare allege that the books of the Bible were not 100% the inspired words of God, the Qur'an was sent down upon Muhammad (pbuh) by God Almighty with the claim that "the people of the Book" had changed the book of God. Muhammad (pbuh) further affirmed that he was sent with the true religion of God which was sent down upon Moses and Jesus (peace be upon them all). The Christians responded that Muslims were ignorant savages who had concocted their own religion by copying Christianity (just as the Jews before them had claimed that the Christians had plagiarized Judaism). I invite the reader to judge for themselves where the truth lies.
Is all of this restricted to the Old Testament? No! Christian scholars today call the Gospels of Matthew, Mark, and Luke, the "Synoptic" (One eyed) Gospels. This is because they all seem to have had access to a common source document they were working from when they wrote their Gospels. This source document is called 'Q'. Now they are beginning to recognize that the alleged authors are not the true authors (see sections 2.1, and 2.2). Similarly, countless verses of the Gospel of John, as well as other historical discrepancies, also go to show that John did not write the Gospel of John.
"Of the Jews are those who change words from their places and say: 'We hear (your words O Muhammad) and disobey; hear you as one who hears not' and 'give us concession' with a twist of their tongues and as a mockery of religion(Islam). But if only they had said: 'We hear and we obey' and 'Do make us understand' it would have been better for them and more upright. But Allah has cursed them for their disbelief, so they believe not, except a few."
The noble Qur'an, Al-Nissa(4):46.
"Do you covet that they will believe in you when [in fact] a party of them used to hear the Word of Allah then they would distort it knowingly after they had understood it?"
The noble Qur'an, Al-Bakarah(2):75
"Then woe to those who write the book (of Allah) with their own hands and then say: 'This is from Allah', to traffic with it for a miserable price. Woe to them for what their hands do write and for the gain they make thereby"
The noble Qur'an Al-Bakarah(2):79
For more on this topic you may obtain any of the books mentioned above.
For More Proof on the Corruption of the Torah
You wouldnt want to forget to check out Corruption of the Torah