Musannaf Ibn Abi Shayba 3:5623

Hushaym narrated to us, he said: Al-Awam informed us, from Ibrahim al-Taymi, who said: Abdullah said: "Indeed, Satan comes to one of you while he is in his prayer, and he pecks at his backside and makes him think that he has broken wind. So if he does that, let not one of you depart until he hears a sound or finds a smell."