There’s an idiom that is used twice in the Koran. First here:
So when she heard of their scheming, she sent for them and prepared for them a banquet and gave each one of them a knife and said [to Joseph], “Come out before them.”
And when they saw him, they greatly admired him and cut their hands and said, “Perfect is Allāh! This is not a man; this is none but a noble angel.”
Koran 12:31
Then later:
12:50 And the king said, “Bring him to me.”
But when the messenger came to him, [Joseph] said, “Return to your master and ask him what is the case of the women who cut their hands. Indeed, my Lord is Knowing of their plan.”
51 Said [the king to the women], “What was your condition when you sought to seduce Joseph?”
They said, “Perfect is Allāh! We know about him no evil.”
The wife of al-ʿAzeez said, “Now the truth has become evident. It was I who sought to seduce him, and indeed, he is of the truthful.
Koran 12:50-51
I believe this is about a pagan oath, cutting the hand to prove one’s honesty, in a culture of lies and deceit. But, I could be wrong.
Conclusion
Muhammad was a false prophet, for a false god, Allah, for a false religion, Islam, without even a false book, the Koran.
Koran Contradiction 