Sunan an-Nasa'i, Volume 2, Book 13, Hadith 1188 (DarusSalam) ⓘ

It was narrated that Zaid bin Aslam said: "Ibn 'Umar said: The Prophet entered the Masjid of Quba' to pray there, then some men came in and greeted him with Salam. I asked Suhaib, who was with him: 'What did the Messenger of Allah do when he was greeted?' He said: 'He used to gesture with his hand.'"

أَخْبَرَنَا مُحَمَّدُ بْنُ مَنْصُورٍ الْمَكِّيُّ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ زَيْدِ بْنِ أَسْلَمَ، قَالَ قَالَ ابْنُ عُمَرَ دَخَلَ النَّبِيُّ صلى الله عليه وسلم مَسْجِدَ قُبَاءَ لِيُصَلِّيَ فِيهِ فَدَخَلَ عَلَيْهِ رِجَالٌ يُسَلِّمُونَ عَلَيْهِ فَسَأَلْتُ صُهَيْبًا وَكَانَ مَعَهُ كَيْفَ كَانَ النَّبِيُّ صلى الله عليه وسلم يَصْنَعُ إِذَا سُلِّمَ عَلَيْهِ قَالَ كَانَ يُشِيرُ بِيَدِهِ ‏.‏