Karayb bin Abi Muslim كريب بن أبي مسلم الهاشمي · The Book on Salat (Prayer)

"I prayed with the Prophet one night. I stood at his left, so Allah's Messenger took me by my head, from behind me, to put me on his right (side)."

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."