Bukhari

Hadith Commentary:
(1)
For an adult, greeting children with salam does not entail any humiliation; rather, it is a part of their education and upbringing, and an expression of affection and love towards them.
Hazrat Anas radi Allahu anhu narrates that the Messenger of Allah sallallahu alayhi wa sallam passed by some children while they were playing, and he greeted them with salam.
(Sunan Abi Dawud, Al-Adab, Hadith: 5202)
In fact, in another narration, it is further clarified that the Messenger of Allah sallallahu alayhi wa sallam would go to meet the Ansar, greet their children with salam, lovingly place his hand on their heads, and supplicate for goodness and blessings for them.
(As-Sunan al-Kubra by an-Nasa’i, Hadith: 8349) (2)
Hafiz Ibn Hajar rahimahullah has written that if there is a fear of falling into temptation (fitnah), then one should not greet a handsome boy with salam, especially when he is adolescent and alone.
(Fath al-Bari: 11/41)
Hazrat Ibn Umar radi Allahu anhu used to greet the children studying in the school with salam.
(Al-Adab al-Mufrad, Hadith: 1044)