Because of the wrongdoing of the Jews We forbade them good things which were (before) made lawful unto them, and because of their much hindering from Allah's way,
-- Sura 4:160
And to those who were Jews We made unlawful all of those who have claws, and of oxen and sheep We made unlawful to them the fat of both, except such as was on their backs or the entrails or what was mixed with bones: this was a punishment We gave them on account of their rebellion, and We are surely Truthful.
-- Sura 6:146
These verses claim that various good things were forbidden to the Jews, and in particular certain parts of the dietary laws were given to them (in addition to the other commandments) because of their disobedience against Allah.
Nothing like that can be found in the Torah or in any other part of the Jewish scriptures. What does the Torah say about the reason for these laws? The reason is given in detail for example in Deuteronomy 4.
In fact, it is exactly the other way around. In a discussion of Jesus with some Jewish teachers of the Torah, we learn this in Matthew 19:
3 Some Pharisees came to him to test him. They asked, "Is it lawful for a man to divorce his wife for any and every reason?" 4 "Haven't you read," he replied, "that at the beginning the Creator `made them male and female,' 5 and said, `For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh'? 6 So they are no longer two, but one. Therefore what God has joined together, let man not separate." 7 "Why then," they asked, "did Moses command that a man give his wife a certificate of divorce and send her away?" 8 Jesus replied, "Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning.
Jesus says clearly that because of their inability to follow the commandments and intentions of God, who hates divorce, it was allowed for them under certain conditions because their hearts were so hard.
Instead of adding prohibitions because of disobedience we see that a permission is given. The law was not made harder but easier. This is the exact opposite of the claim of the Qur'an.
We also need to discuss the problem of historical confusion about the time the dietary laws were given.
Remarks on the various translations:
The above is basically the translation of Shakir, who agrees with Pickthall in translating this distinguishing property as "claws". Yusuf Ali mistranslates instead as "For those who followed the Jewish Law, We forbade every (animal) with undivided hoof, ..." (maybe) to bring the statement in the Qur'an more in line with the Biblical command in Leviticus 11 where we find the allowance of animals with split hooves in verse 3. But the Arabic does not say "undivided hoof" but "claws".
The Qur'an is in error again. There is no general prohibition against animals with claws in the Torah either. For example, pidgeons or chicken are kosher and may be eaten, but they have claws. Some animals with claws are forbidden, but not all.
The word in Arabic is "Thufur" and means in respect to humans: Nail. Claw or talon for birds and animals. That is according to the Arabic-English dictionnary "Al-kamoos Al-Asri".
On the other hand, according to the same source, the word "hoof", cloven or split, is the translation for the Arabic word "Thilif".
The word "thufur" is the one used in Sura 6:146.
All of the translations by Shakir, Pickthall and Yusuf Ali add the word "animal" which is not there in the Arabic either.
In particular, we see that the Torah forbids certain birds, but other birds (like pidgeons, chicken, etc.) are lawful. And birds do have claws.
Side remark: Most kosher food is also halal. In this sense the dietary laws of the Jews are more strict than those of the Muslims. That is true. But the issue is not whether they are strict or not, but whether this is because of punishment for disobedience or not.
Yet there is at least one item where Islam is more strict. Alcohol is completely forbidden in Islam, while it is allowed in the Bible. The following link gives a good overview article on the issue of alcohol in the Bible.
Contradictions in the Qur'an
Answering Islam Home Page