I offered prayer along with the Prophet (ﷺ). He would give the salutation to his right side (saying): Peace be upon you and the mercy of Allah and His blessings; and to his left side (saying): Peace be upon you and mercy of Allah.
Sunan Abi Dawud Book 2, Hadith 608
← Previous Hadith The Prophet (ﷺ) used to give the salutation to his left and right sides until the whiteness of his cheek was seen, (saying: "Peace be upon you, and mercy of Allah" twice.

AbuDawud said: This is a version of the tradition reported by AbuSufyan. The version of Isra'il did not explain it. AbuDawud said: This tradition has been narrated by Zubayr from AbuIshaq and Yahya ibn Adam from Isra'il from AbuIshaq from AbdurRahman ibn al-Aswad from his father from Alqamah on the authority of Abdullah ibn Mas'ud. AbuDawud said: Shu'bah used to reject this tradition, the tradition narrated by AbuIshaq as coming from the Prophet (ﷺ).

Sunan Abi Dawud Book 2, Hadith 607 Next Hadith → When we prayed behind the Messenger of Allah(ﷺ), one of us gave the salutation and pointed with his hand to the man to his right side and left side. When he finished his prayer, he said: What is the matter that one of you points with his hand (during prayer) just like the tails of restive horses. It is sufficient for one of you, or is it not sufficient for one of you to say in this manner? And he pointed with his finger; one should salute his brother at his right and left side.

Sunan Abi Dawud Book 2, Hadith 609