Abu Huraira (may Allah be pleased with him) narrated from the Messenger of Allah (peace and blessings be upon him), he (peace and blessings be upon him) said: "By Him in Whose hand is the soul of Muhammad (peace and blessings be upon him)! You will not enter Paradise until you believe, and you will not believe until you love one another. Shall I not tell you of something which, if you do it, you will love one another?" They said: O Messenger of Allah! What is that? He (peace and blessings be upon him) said: "Spread salam (greetings of peace) among yourselves."