Abu Hurairah reported the Messenger of Allah ﷺ as saying; 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 has such an experience, he should perform two prostrations while he is sitting. Abu Dawud said; This tradition has been narrated in a similar manner by Ibn ‘Uyainab, Ma’mar and al-Laith. (Using translation from Abū Dāʾūd 1030)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «إِنَّ أَحَدَكُمْ إِذَا قَامَ يُصَلِّي جَاءَهُ الشَّيْطَانُ فَلَبَّسَ عَلَيْهِ حَتَّى لَا يَدْرِي كَمْ صَلَّى فَإِذَا وَجَدَ ذَلِكَ أَحَدُكُمْ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ»