Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 991
Narated By Abdullah ibn Mas'ud : The Prophet (pbuh) 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 (pbuh).