Sunan at-Tirmithiy كتاب الاستئذان والآداب باب ما جاء فى إفشاء السلام
The Messenger of God, peace and blessings of God be upon him, said, “By the One in whose Hand my soul is, you will not enter Paradise until you believe, and you will not believe until you love one another. Shall I not guide you towards an act which, if you were to do, you would love one another? Spread the greetings of peace among you.” Click on ḥadīth to read more