It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that when any one of you is performing prayer, Satan comes to him and confuses him, to the extent that he does not remember how many rak'ahs he has performed. Whoever experiences such a situation should, when he sits in the final sitting (qa'dah akheerah), perform two prostrations of forgetfulness (sujood as-sahw).