Returning the salams with a gesture when praying
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 .
It was narrated that Zaid bin Aslam said: "Ibn 'Umar said: The Prophet (ﷺ) 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 (ﷺ) do when he was greeted?' He said: 'He used to gesture with his hand.'"