Jami` at-Tirmidhi 397
جامع الترمذي#397SahihAbu Hurairah narrated that:Allah's Messenger (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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 2:250