Musnad Abu Ya'la al-Mawsili 148:2

Abu Bakr ibn Abi Shaybah narrated to us, Yazid ibn Harun narrated to us, from Muhammad ibn Ishaq, from Yazid ibn Abi Habib, from Sa'id ibn Sinan, from Anas ibn Malik, who said: I heard the Messenger of Allah say: "He is not a believer whose neighbor is not safe from his harm."