The Prophet ﷺ entered the mosque of Quba to pray in it, and some men came in to greet him. I asked Suhayb, who was with him, how the Prophet ﷺ used to respond when greeted.He said, "He would gesture with his hand."
أخبرنا محمد بن منصور المكي قال حدثنا سفيان عن زيد ابن أسلم قال
دخل النبي ﷺ مسجد قباء ليصلي فيه فدخل عليه رجال يسلمون عليه فسألت صهيبا وكان معه كيف كان النبي ﷺ يصنع إذا سلم عليه قال كان يشير بيده
Its isnad is sahih. Ibn Majah reported it in the chapter on establishing prayers, section on the one praying being greeted, how he should respond, hadith 1017, from the hadith of Sufyan bin Uyayna, with this wording. It is also in al-Kubra, hadith 1110. Ibn Khuzayma graded it sahih, as did Ibn Hibban (al-Ihsan), hadith 2258, and Hakim, 12/3, and Dhahabi. It has many corroborating narrations, see the hadith that follows at number 1190.(Zayd bin Aslam explicitly stated that he heard it directly, as recorded by Ibn Khuzayma, 49/2, hadith 888, and he was not, according to the more correct view, a mudallis.)