Sunan Ibn Majah 3695
سنن ابن ماجه#3695SahihIt was narrated from Abu Hurairah that:"a man entered the masjid, and the Messenger of Allah(ﷺ) was sitting in a corner of the mosque. He prayed, then he came and greeted him with Salam(peace), and he said: 'Wa 'alaikassalm
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 33:39