If the Torah and Gospel are corrupt, then the Qur’an is false; and if the Torah and Gospel are the words of Allah, then the Qur’an is false.

So if you are in doubt, [O Muhammad], about that which We [Allah] have revealed to you, then ask those who have been reading the Scripture before you. The truth has certainly come to you from your Lord, so never be among the doubters.”
Surah Yunus [10:84] | The Qur’an (referring to the Bible)

He was to ask the people of the book

Mohammed was in doubt of his revelations

Mohammed was in doubt of his revelations from Allah and was told by Allah himself (according to the Qur’an) to consult the Torah and Gospel (the Bible) for truth (Surah 10:84).

Look what the Qur’an says about the Bible! 

It says Allah himself gave the Torah and the Gospel

He [Allah] has sent down upon you, [O Muhammad], the Book in truth, confirming what was before it. And He revealed the Torah and the Gospel.”
Surah Ali ‘Imran [3:3] | The Qur’an

And He will teach him writing and wisdom and the Torah and the Gospel.”
Surah 3:50 | The Qur’an

The Qur’an goes on to to say that Allah and the God of the Torah and Gospels are the same

And do not argue with the People of the Scripture except in a way that is best, except for those who commit injustice among them, and say, “We believe in that which has been revealed to us and revealed to you. And our God and your God is one; and we are Muslims [in submission] to Him.”
Surah Al-’Ankabut [24:46] | The Qur’an

But the Qur’an opposes the Bible!

How can the Qur’anic god, Allah and the Biblical God, Yahweh be the same God when there are major contradictions from what each of the two books proclaim as being true?

If the Qur’an clearly states that Allah and Yahweh are the same God as quoted above, (and that “He” gave both the Scriptures before and the Qur’an afterwards); how then can there be such blatant discrepancies between each of the two books in what they teach as being true?

Qur’an:

• Allah has no son (Surah 6:101) 
• Denies that Jesus died on the cross (Surah 4:157-158)
• Slay non-Muslims (Surah 9:5) 
• Kill those against Islam (Surah 5:33) 
• Behead those who oppose Allah (Surah 8:12)

The answer is simple—Muslims claim that the Bible is corrupted (changed)

Yet, the Qur’an confirms the Bible has never been corrupted

Muslims repeatedly claim that the Bible has been corrupted and that the Qur’an is the only trustworthy scripture in existence. This is why Muslims often attack the Bible. But this cannot be according to the Qur’an. The Qur’an says that the books of Moses, the Psalms, and the Gospel were all given by Allah as we have already read above. Furthermore, it goes on to proclaim that NO ONE—NONE, can change Allah’s words:

The word of thy Lord doth find its fulfillment in truth and in justice: None can change His words: for He [Allah] is the one who heareth and knoweth all,”
Surah 6:34 | The Qur’an

So why do Muslims reject the Bible if the Qur’an says that none can change his words?

Regardless of what the Qur’an says as stated earlier, Muslims still do not accept what their own book tells them 

Because they choose not to believe their own book and turn to the Gospel

Even when presented with actual quotes of exactly what the Qur’an clearly states:

• Allah gave the Qur’an as did he with both the Torah and the Gospel;
• Allah and Yahweh are one and the same God;
• None can change His words—NONE, therefore the Torah and the Gospels could not have been corrupted nor changed either;

The Muslim still refuses to accept their own Qur’anic text and reject the biblical Scripture (Torah) and the Gospel as being true.

The Muslim is left with only one possible conclusion because of what the Qur’an states: 

1. Either the Torah and Gospel are corrupt
   (of which the Qur’an states that they can not be and in fact are not,)
   …then that would make the Qur’an false—because the gospel says that God has a Son and He rose from the dead;
   
2. Or, the Torah and Gospel are Allah’s words
   (of which the Qur’an states that they in fact are his words,)
   …then that would make the Qur’an false—because the Qur’an says that Allah had no son and that Jesus did not die nor was He raised from the dead. 

Concluding…

 
Therefore, If the Torah and Gospel are corrupt, then the Qur’an is false; and if the Torah and Gospel are the words of Allah, then the Qur’an is false.”

He [Allah] has sent down upon you, [O Muhammad], the Book in truth, confirming what was before it. And He revealed the Torah and the Gospel.”
Surah Ali ‘Imran [3:3] | The Qur’an