Musnad Ahmad 31:347

Abu Abd al-Rahman narrated to us, Haywah narrated to us, Salim ibn Ghaylan informed us, that al-Walid ibn Qays al-Tujibi informed him that he heard Abu Sa’id al-Khudri—or from Abu al-Haytham, from Abu Sa’id al-Khudri—that he heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Do not keep company except with a believer, and let no one eat your food except a God-fearing person."