Do you think that you could enter paradise unless God takes cognizance of your having striven hard [in His cause], and takes cognizance of your having been patient in adversity?
Al-Imran (The Family of Imran) Verse 142
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
Sahih Bukhari: Volume 1, Book 2, Number 11