(V.69:34)
a) See the footnote of (V.2:83).
b) Narrated ‘Abdullâh bin ‘Amr رضي الله عنه: A man asked the Prophet صلى الله عليه وسلم, "What sort of deeds (or what qualities) of Islâm are good?" The Prophet صلى الله عليه وسلم replied, "To feed (the poor) and greet those whom you know and those whom you do not know". (Sahih Al-Bukhari, Vol.1, Hadith No.11).