It was narrated that Ibn 'Abbas (رضي الله عنه) said: The Messenger of Allah (ﷺ) said:

“When Pharaoh said ‘I believe that none has the right to be worshipped but He (Allah) in Whom the Children of Israel believe’ (Yoonus 10:90). Jibreel said to me: 'O Muhammad, if only you could have seen me when I took some mud of the sea and stuffed it into his mouth lest he attain mercy.”