From Sahih Bukhari (Hadith 445):
Narrated Abu Huraira:Allah's Messenger (ﷺ) said, "The angels keep on asking Allah's forgiveness for anyone of you, as long as he is at his Musalla (praying place) and he does not pass wind (Hadath). They say, 'O Allah! Forgive him, O Allah! be Merciful to him
Reference: Bukhari 445