It is narrated from Sayyiduna Abu Hurairah, may Allah be pleased with him: The Messenger of Allah, peace and blessings be upon him, said: "When the call to prayer (adhan) is given, Satan turns his back and flees while passing wind so that he does not hear the adhan. When the adhan is finished, he returns, and when the iqamah is pronounced, he flees again. When the iqamah is finished, he comes back and continues to cast doubts into the heart of a person, saying, 'Remember such and such, remember such and such,' reminding him of things he did not recall before, to the extent that the person does not remember how many units (rak‘ahs) he has prayed. So if any of you does not remember whether he has prayed three or four rak‘ahs, he should perform two prostrations while sitting (i.e., perform the prostration of forgetfulness—sajdah sahw)."