The Messenger of Allah ﷺ said, "Let the younger greet the older, the one passing by greet the one sitting, and the smaller group greet the larger."
وقال رسول الله ﷺ ليسلم الصغير على الكبير والمار على القاعد والقليل على الكثير
This is sahih like the one before it. It is in the Sahifah Mufradah, number 49, and Bukhari related it [8:52 Tabari edition / 11:13 Fath, from her route, then narrated after it - similarly - through other channels. Muslim did not narrate it through the route of the Sahifah, but he narrated something similar through another channel, 2:174 Bulaq edition.As for his statement, "let him submit" (li-yuslim), it is recorded this way with the lam of command at its beginning in the three original copies of the Musnad. In the Sahifah Mufradah it appears as "he submits" (yuslim), without the lam. This agrees with what is in Jami al-Masanid wal-Sunan and with Bukhari's narration.