Musnad Ahmad 7:26

'Abd al-Rahman narrated to us, Harb ibn Shaddad narrated to us, from Yahya ibn Abi Kathir, that Ya'ish ibn al-Walid narrated to him, that a freed slave of the family of al-Zubayr narrated to him, that al-Zubayr ibn al-'Awwam narrated to him, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "There has crept upon you the disease of the nations before you: envy and hatred. And hatred is the shaver; I do not say it shaves the hair, but it shaves the religion. By the One in Whose hand is my soul—or 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 inform you of that which will establish that for you? Spread the greeting of peace (salam) among yourselves."