The Book of Prayers (Kitab Al-Salat)

Muslim :: Book 4 : Hadith 1161

Abu Huraira reported: The Messenger of Allah (may peace be upon him) said: When there is a call to prayer the devil runs back breaking the wind so that he may not hear the call, and when the call is complete he comes back. And when the takbir is pronounced he again runs back, and when takbir is over he comes back and distracts a man saying: Remember such and such, remember such and such, referring to something the man did not have in his mind. with the result that he does not know how much he has prayed; so when any one of you is not sure how much he has prayed. he should perform two prostrations while sitting (qa'da).