Sunan Abi Dawud 1021
سنن أبي داود#1021SahihThis tradition has also been transmitted by ‘Abd Allah (b. Mas’ud) through a different chain of narrators. This version goes; when one of you forgets (in his prayer), he should perform two prostrations. Then he turned away, and performed two prostrations (due to forgetfulness). Abu Dawud said:The narrator Husain also reported it like al-A'mash
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim (572)
In-book reference: 2:632