أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا عَبْدُ الْعَزِيزِ، - يَعْنِي الدَّرَاوَرْدِيَّ - عَنْ عَمْرِو بْنِ يَحْيَى، عَنْ مُحَمَّدِ بْنِ يَحْيَى بْنِ حَبَّانَ، عَنْ عَمِّهِ، وَاسِعِ بْنِ حَبَّانَ، قَالَ قُلْتُ لاِبْنِ عُمَرَ أَخْبِرْنِي عَنْ صَلاَةِ، رَسُولِ اللَّهِ صلى الله عليه وسلم كَيْفَ كَانَتْ قَالَ فَذَكَرَ التَّكْبِيرَ قَالَ يَعْنِي وَذَكَرَ ‏"‏ السَّلاَمُ عَلَيْكُمْ وَرَحْمَةُ اللَّهِ" عَنْ يَمِينِهِ, "السَّلاَمُ عَلَيْكُمْ" عَنْ يَسَارِهِ."‏

It was narrated from 'Abdullah that

The Prophet (ﷺ) used to say salam to his right and to his left: As-salamu 'alaykum wa rahmatullah, as-salamu alaykum wa rahmatullah (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 here, and the whiteness of his cheek from here.