It was narrated that ‘Abdullah (رضي الله عنه) said:

I did not forget, among the things I forgot from The Messenger of Allah (ﷺ), that he used to say salam to his right, as-salamu 'alaikum wa rahmutullah, (turning) so far that the whiteness of his cheek could to seen, and to his left, as-salamu ‘alaikum wa rahmatullah, (turning) so far that the whiteness of his cheek could be seen.