Musnad Ahmad 28:145

Hassan narrated to us, Ibn Lahi'ah narrated to us, Huyayy ibn Abdullah narrated to me, from Abu Abd al-Rahman al-Hubuli, from Abdullah ibn Amr: That the Messenger of Allah, peace and blessings of Allah be upon him, said: "Whoever believes in Allah and the Last Day, let him honor his guest. And whoever believes in Allah and the Last Day, let him protect his neighbor. And whoever believes in Allah and the Last Day, let him speak good or remain silent."