What is the main topic of Riyad us Saliheen Hadith 862?

Riyad us Saliheen Hadith 862 is from chapter "The Book of Greetings". Summary: "Messenger of Allah (ﷺ) used to do the same." [Al-Bukhari and Muslim].

Riyad us Saliheen: Hadith 862

6. The Book of Greetings

862

Riyad us Saliheen

عن أنس رضي الله عنه أنه مر على صبيان، فسلم عليهم، وقال‏:‏ كان رسول الله صلى الله عليه وسلم يفعله” ‏(‏‏(‏متفق عليه‏)‏‏)‏

Anas (May Allah be pleased with him) reported that he passed by some children and greeted them. Then he said:

"Messenger of Allah (ﷺ) used to do the same."

[Al-Bukhari and Muslim].

Reference: Sunnah.com : Book 6, Hadith 18
Arabic/English book : Book 6, Hadith 862