Sahih Bukhari, Hadith No. 12: Narrated Abdullah bin Amr (R.A): A man asked the Prophet (S.A.W), "What sort of deeds or (what qualities of) Islam are good?" The Prophet (S.A.W) replied, "To feed (the poor) and greet those whom you know and those whom you do not know".

Sahih Bukhari, Hadith No. 12

Narrated Abdullah bin Amr (R.A): A man asked the Prophet (S.A.W), "What sort of deeds or (what qualities of) Islam are good?" The Prophet (S.A.W) replied, "To feed (the poor) and greet those whom you know and those whom you do not know".