Ibn Shihab (al-Zuhr) reported on the authority of Abu Bakr bin Sulaiman bin Abi Hathmah that the Messenger of Allah صلی اللہ علیہ وسلم did not make two prostrations when are made when one is doubtful until the people met him. Abu Dawud said; this tradition has also been transmitted by al-Zahidi from al-zuhr from Abu Bakr bin Sulaiman bin Abi HAthman from thre prophet صلی اللہ علیہ وسلم . This version goes: he did not make two prostrations on account of forgetfulness.

Narrated Abdullah ibn Masud: The Messenger of Allah صلی اللہ علیہ وسلم offered prayer. The version of the narrator Ibrahim goes: I do not know whether he increased or decreased (the rak'ahs of prayer). When he gave the salutation, he was asked: Has something new happened in the prayer, Messenger of Allah? He said: What is it? They said: You prayed so many and so many (rak'ahs). He then relented his foot and faced the Qiblah and made two prostrations. He then gave the salutation. When he turned away (finished the prayer), he turned his face to us and said: Had anything new happened in prayer, I would have informed you. I am only a human being and I forget just as you do; so when I forget, remind me, and when any of you is in doubt about his prayer he should aim at what is correct, and complete his prayer in that respect, then give the salutation and afterwards made two prostrations.

Ata bin Yasar said that Abu Saeed Al-Khudri reported the Messenger of Allah صلی اللہ علیہ وسلم as saying: when one of you is in doubt about his prayer (i. e, how much he has prayed), he should throw away his doubt and base his prayer on what he is sure of. When he is sure about the completion of his prayer, he should make two prostrations (at the end of the prayer). If the prayer is complete, the additional rak’ah and the two prostrations will be supererogatory prayer. If the prayer is incomplete, the additional rak’ahs will compensate it, and the two prostrations will be a disgrace for the devil.