Al Ghazali and Bukhari believed in the authenticity of the Torah and the Injiel that were at that time in
The Qur’an says of itself that it is preserved on golden tablets in heaven (Surah 85:21-22), and nowhere it says that the Bible (NT) and the Torah (OT) are corrupted. The Qur’an instead says that there is a specific group of unlettered Jews, ignorant of the Scriptures, that falsified (with their tongue) the Revelation, in order to gain some money. Ibn Kathir quotes Wah ibn Munabbih that states "their interpretation is false, they wrote their books by themselves”.
But, there is a long list of Surahs that confirm the Scriptures. Here they are: 5:48; 5:68; 6:91-2; 6:115; 10:37 and 10:94. They all state that a) the Scriptures already existed at Muhammad’s time and b) that they were not corrupted, except if we want to believe that the Qur’an makes appeal to corrupted books (example: Surah 12:111; 16:43; 21:7; 21:105; 20:133; 26:196 and 28:48-9). Muhammad is ordered to defend the veracity and authority of the Torah that existed at that time (this shows that it wasn’t corrupted, otherwise, how could Muhammad defend a corrupted revelation?). Surah 40:53; 87:18-9 and 2:113 prove that the Torah and the Bible are not corrupted, otherwise, how can one testify for the other?
Bukhari for example, agrees that the Bible could not be changed, because it is the Word of God. Some centuries had to pass before that Muslims could say that the Scriptures were manipulated (the first idea came late in
Muhammad makes appeal to two verses that would confirm his prophecy (the problem is that there is no way to extrapolate this from the Bible, but on that later. Moreover, the actual text that we have now is the same that was available in the seventh century. The Qur’an never says of any corruption of the Bible, it only says to compare the two Scriptures. The other problem is that the Bible has been translated in Arabic only after the Qur’an. So, there were no chances to compare them.