Sunan Ibn Majah
916
Sahih+2

It was narrated that ‘Ammar bin Yasir said:“The Messenger of Allah (ﷺ) used to say the Salam to his right and to his left, until the whiteness of his cheek could be seen (saying): ‘As-salamu ‘alaikum wa rahmatullah, as-salamu ‘alaikum wa rahmatullah.’”

SahihAl-Albani
Sahih LighairihiMuhammad Fouad Abd al-Baqi