Narrated Abu Hurairah:that the Messenger of Allah (ﷺ) said: "By the One in Whose Hand is my soul! You will not enter Paradise until you believe, and you will not believe until you love one another. Shall I inform you about a matter which if you do it, then you will love one another? Spread the Salam among each other"
SahihSahihHasan SahihBook 42 · Hadith 1