Musnad Ahmad 1301:26

Abu Mu'awiyah narrated to us, from al-A'mash, from 'Amr ibn Murrah, from Salim ibn Abi al-Ja'd, from Umm al-Darda', from Abu al-Darda', who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Shall I not inform you of something better in degree than prayer, fasting, and charity?" They said: "Yes." He said: "Reconciling between people." And he said: "And corrupting the relationship between people is the shaver."