The Prophet ﷺ said: You shall not enter Paradise until you believe, and you have not believed until you love one another. Shall I tell you of something you can do to make you love one another? Spread the greetings of Salam amongst yourselves (i.e. between each other).
There are three things which whoever gathers all of them together, then he has gathered Imaan (Faith): justice with oneself, greeting people with greetings of Salam (peace), and freeing oneself from stinginess.
Abdullah bin Umar said: A man asked the Prophet ﷺ, What is the best act of Islam? He said: “To feed others and to give greetings of Salam to those whom you know and to those whom you do not know.
