Yahya related to me from Malik that Yahya ibn Said said that heheard Said ibn al-Musayyab say, "Shall I tell you what is better thanmuch prayer and sadaqa?" They said, "Yes." He said, "Mending discord.And beware of hatred - it strips you (of your deen)."
USC-MSA web (English) reference: Book 47, Hadith 7
Arabic reference: Book 47, Hadith 1642