Those Who Said He Should Complete (The Prayers) Based Upon His Strongest Judgement Sunan Abi Dawud 1030
Translation
When one of you stands up to pray, the devil comes to him and confuses him so that he does not know how much he has prayed. If any of you experiences that, he should perform two prostrations while he is sitting.
Abu Dawud said: And thus it was narrated by Ibn ‘Uyaynah, Ma‘mar, and al-Laith.