Messenger of Allah (S) said: "Indeed the Shaitan comes to one of you in his Salat confusing him until he does now know how much he has prayed. When one of you experiences that then let him perform two prostrations while sitting." (Using translation from Tirmidhī 397)
أَنَّهُ قَالَ قَالَ رَسُولُ اللهِ ﷺ يَأْتِي أَحَدَكُمُ الشَّيْطَانُ وَهُوَ فِي صَلَاتِهِ فَيَلْبِسُ عَلَيْهِ حَتَّى لَا يَدْرِيَ كَمْ صَلَّى فَإِذَا وَجَدَ ذَلِكَ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ