Various passages tell the story that Pharaoh's sorcerers believe in the signs and message of Moses, and then Pharaoh tries to threaten them with these words (Shakir's translation):
I will certainly cut off your hands and your feet on opposite sides, then will I crucify you all together. [Surah 7:124]
Said he: You believe in him before I give you permission; most surely he is the chief of you who taught you the magic, so you shall know: certainly I will cut off your hands and your feet on opposite sides, and certainly I will crucify you all. [Surah 26:49]
In the story of Joseph, about 400 years earlier we also read of another crucifixion in this passage:
O my two mates of the prison! as for one of you, he shall give his lord to drink wine; and as for the other, he shall be crucified, so that the birds shall eat from his head, the matter is decreed concerning which you inquired. [Surah 12:41]
We have, however, no record that Egyptians used crucifixion as punishment in the time of Moses (1450 BC, conservative date; 1200 BC at the latest) or even Joseph (1880 BC, conservative date). Crucifixion only becomes a punishment much later in history and then first in another culture before it has been taken over by the Egyptians. Such threats by a Pharaoh at these times are historically inaccurate.
This topic has resulted in much debate. The latest discussion can be found in the article Crucifixion Or 'Crucifiction' In Ancient Egypt?
Contradictions in the Qur'an
Answering Islam Home Page