Sayyidina Abu Huraira (RA) reported that Allah’s Messenger (SAW) said, “By Him in Whose Hand is my life, you will not enter Paradise till you believe, and you will not believe till you love each other. Shall I not guide you to something which if you do, you will love each other. Give currency to salaam between yourselves.”
[Muslim 54, Bukhari 260, Abu Dawud 5193, Ibn Majah 68, Ahmed 10436]