that he passed by a group of boys and greeted them and said, "The Prophet ﷺ used to do so."  

أَنَّهُ مَرَّ عَلَى صِبْيَانٍ فَسَلَّمَ عَلَيْهِمْ وَقَالَ كَانَ النَّبِيُّ ﷺ يَفْعَلُهُ