Hadith 1218
It was narrated from ‘Alqamah that Ibn Mas’ud prostrated twice for the prostrations of forgetfulness after the Salam, and he mentioned that the Prophet (ﷺ) did that.”
Hadith 1219
´It was narrated that Thawban said:` “I heard the Messenger of Allah (ﷺ) say: ‘For every mistake there are two prostrations, after saying the Salam.’”