Ya"eesh bin al-Waleed narrated that a freed slave of the family of az-Zubair told him that azZubair bin al-"Awwam (رضي الله عنه) narrated to him that

The Messenger of Allah (ﷺ) said: “There has come to you the disease of the nations before you, jealousy and hatred. Hatred is the "shaver" (destroyer). I do not say that it shaves hair; rather its shaves (destroys) religious commitment. By the One in Whose Hand is the soul of Muhammad, 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 that will help you to achieve that? Spread (the greeting of) salaam amongst yourselves."