"I said to Ibn 'Umar: "Tell me about the prayer of the Messenger of Allah ﷺ; how was it?" He mentioned the takbir and he mentioned: As-salamu 'alaykum wa rahmatullah (peace be upon you and the mercy of Allah) to his right and: As-salamu 'alaykum (peace be upon you) to his left." (Using translation from Nasāʾī 1321)
أَخْبِرْنِي عَنْ صَلَاةِ رَسُولِ اللهِ ﷺ كَيْفَ كَانَتْ؟ قَالَ فَذَكَرَ التَّكْبِيرَ كُلَّمَا وَضَعَ رَأْسَهُ وَكُلَّمَا رَفَعَهُ وَذَكَرَ السَّلَامُ عَلَيْكُمْ وَرَحْمَةُ اللهِ عَنْ يَمِينِهِ السَّلَامُ عَلَيْكُمْ عَنْ يَسَارِهِ