Suhaib narrated:

"I passed by Allah's Messenger (S) while he was performing Salat, so I said greeted him with Salam, and he returned it by making signals." He said: "I do not know except that he said: 'He indicated with his finger.'"

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ بُكَيْرِ بْنِ عَبْدِ اللَّهِ بْنِ الأَشَجِّ، عَنْ نَابِلٍ، صَاحِبِ الْعَبَاءِ عَنِ ابْنِ عُمَرَ، عَنْ صُهَيْبٍ، قَالَ مَرَرْتُ بِرَسُولِ اللَّهِ ﷺ وَهُوَ يُصَلِّي فَسَلَّمْتُ عَلَيْهِ فَرَدَّ إِلَىَّ إِشَارَةً . وَقَالَ لاَ أَعْلَمُ إِلاَّ أَنَّهُ قَالَ إِشَارَةً بِإِصْبَعِهِ . قَالَ وَفِي الْبَابِ عَنْ بِلاَلٍ وَأَبِي هُرَيْرَةَ وَأَنَسٍ وَعَائِشَةَ .