Ali reported that the Prophet ﷺ used to give the salutation to his right and to his left, saying, "Peace be upon you and the mercy of Allah, peace be upon you and the mercy of Allah," until the whiteness of his cheek could be seen from this side and the whiteness of his cheek from that side.
أخبرنا عمرو بن علي قال حدثنا عبد الرحمن عن سفيان عن أبي إسحق عن أبي الأحوص
عن النبي ﷺ أنه كان يسلم عن يمينه وعن يساره السلام عليكم ورحمة الله السلام عليكم ورحمة الله حتى يرى بياض خده من هاهنا وبياض خده من هاهنا