"The Messenger of Allah ﷺ sent me on an errand, then I came back to him while he was facing the east or the west. I greeted him with salam and he gestured to me. Then when he finished he called me and said: "O Jabir!" So I came and said: "O Messenger of Allah, I greeted you with Salam but you did not answer." He said: 'I was praying.' (Using translation from Nasāʾī 1190)   

بَعَثَنِي النَّبِيُّ ﷺ فَأَتَيْتُهُ وَهُوَ يَسِيرُ مُشَرِّقًا أَوْ مُغَرِّبًا فَسَلَّمْتُ عَلَيْهِ فَأَشَارَ بِيَدِهِ ثُمَّ سَلَّمْتُ فَأَشَارَ بِيَدِهِ فَانْصَرَفْتُ فَنَادَانِي النَّاسُ يَا جَابِرُ فَأَتَيْتُهُ فَقُلْتُ يَا رَسُولَ اللهِ إِنِّي سَلَّمْتُ عَلَيْكَ فَلَمْ تَرُدَّ عَلَيَّ فَقَالَ «إِنِّي كُنْتُ أُصَلِّي» قَالَ أَبُو عَبْدِ الرَّحْمَنِ زَعَمُوا أَنَّهُ لَيْسَ هَذَا الْحَدِيثُ بِمِصْرَ مِنْ حَدِيثِ عَمْرِو بْنِ الْحَارِثِ