Sahih Bukhari Volume 1, Book 2, Hadith Number 11

Narated By ‘Abdullah bin ‘Amr : A man asked the Prophet, “What sort of deeds or (what qualities of) Islam are good?” The Prophet replied, ‘To feed (the poor) and greet those whom you know and those whom you do not know’ (See Hadith No. 27).


Reference: Sahih al-Bukhari 12
In-Book Reference: Sahih al-Bukhari Book 2 Hadith 5