The Messenger of Allah ﷺ used to say salam to his right:As-salamu 'alaykum wa rahmatullah (peace be upon you and the mercy of Allah) , until the whiteness of his right cheek could be seen, and to his left: As-salamu 'alaykum wa rahmatullah (peace be upon you and the mercy of Allah) until the whiteness of his left cheek could be seen. (Using translation from Nasāʾī 1325)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُسَلِّمُ عَنْ يَمِينِهِ «السَّلَامُ عَلَيْكُمْ وَرَحْمَةُ اللهِ» حَتَّى يُرَى بَيَاضُ خَدِّهِ الْأَيْمَنِ وَعَنْ يَسَارِهِ «السَّلَامُ عَلَيْكُمْ وَرَحْمَةُ اللهِ» حَتَّى يُرَى بَيَاضُ خَدِّهِ الْأَيْسَرِ