(172) باب رَدِّ السَّلاَمِ فِي الصَّلاَةِ
Abu Hurairah reported the Prophet (ﷺ) as saying:
There is no loss in prayer nor in salutation. Ahmad(b. Hanbal) said: This means, I think, that you do not salute nor you are saluted by others. The loss of a man in his prayer is that a man remains doubtful about it when he finishes it.
Reference: Sunan Abi Dawud 928
In-book reference: Book 2, Hadith 539
English translation: Book 2, Hadith 928