The Quran Verse
Surah 12:31
"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 Allah! This is not a man; this is none but a noble angel.'"
The Relevant Source Text (Jewish Midrash)
Midrash Tanhuma (Yelammedenu), Vayeshev 5
"She [Zuleikha] invited all the princesses of Egypt... she put etrogs (citrus fruits) before them and gave each one a knife. Then she called Joseph and stood him before them. When they beheld the beauty of Joseph, they cut their hands with the knives..."
This striking detail is found NOWHERE in the Book of Genesis. It is a 5th-century AD Jewish legendary embellishment designed to emphasize Joseph’s physical beauty.
The Quran adopts this late Rabbinic "urban legend" and presents it as a historical event revealed by God. To the critic, this proves the Quranic author was listening to local Jewish storytellers in Arabia and mistaking their sermons (Haggadah) for divine scripture.