Jami` at-Tirmidhi, Volume 5, Book 44, Hadith 3107 (DarusSalam) ⓘ
Narrated Ibn 'Abbas: that the Messenger of Allah said: "When Allah drowned Fir'awn he said: 'I believe that there is no god except the One that the children of Isra'il believe in.' So Jibrail said: 'O Muhammad! If you could only have seen me, while I was taking (the mud) from the sea, and filling his mouth out of fear that the mercy would reach him.'"
حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، حَدَّثَنَا الْحَجَّاجُ بْنُ مِنْهَالٍ، حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ عَلِيِّ بْنِ زَيْدٍ، عَنْ يُوسُفَ بْنِ مِهْرَانَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " لَمَّا أَغْرَقَ اللَّهُ فِرْعَوْنَ قَالَ آمَنْتُ أَنَّهُ لاَ إِلَهَ إِلاَّ الَّذِي آمَنَتْ بِهِ بَنُو إِسْرَائِيلَ فَقَالَ جِبْرِيلُ يَا مُحَمَّدُ فَلَوْ رَأَيْتَنِي وَأَنَا آخُذُ مِنْ حَالِ الْبَحْرِ فَأَدُسُّهُ فِي فِيهِ مَخَافَةَ أَنْ تُدْرِكَهُ الرَّحْمَةُ " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ .
also referenced under: Hadith 3107 (Reference) & Book 47, Hadith 3392 (In-Book)