Musnad Abu Ya'la al-Mawsili 155:153

On the authority of Abu Salamah, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When the caller calls out [the Adhan], the Shaytan turns his back, passing wind so that he does not hear the call. When he finishes, he returns. When the Iqamah is called, he turns his back. When it is finished, he returns until he inserts himself between a man and his own self, saying: 'Remember such-and-such, remember such-and-such,' regarding things he did not remember, until he does not know whether he prayed three [rak'ahs] or four. So if one of you does not know whether he prayed three or four, let him perform two prostrations while he is sitting."