The Quran Verse
Surah 10:90–92
...Then when he was on the point of drowning, he said, 'I believe that there is no god but Him in whom the tribe of Israel believes...' Allah said: 'Today We will save you in your body that you may be a sign to those who come after you...'
This narrative directly contradicts the biblical account in Exodus 14, where Pharaoh and his entire army are simply destroyed in the sea with NO mention of his last-minute conversion or the preservation of his corpse.
Historical critics argue this "sign" was a 7th-century attempt to explain why the Israelites didn't see Pharaoh's body or to dramatize the futility of death-bed repentance.
Some scholars point to Jewish Midrashic traditions (such as Pirkei De-Rabbi Eliezer) which sometimes suggested Pharaoh survived to become the King of Nineveh, or legends where his body was cast out of the sea to prove his death to the skeptical Israelites. The Quran canonizes these local legendary elaborations as historical facts.