Musnad Abu Ya'la al-Mawsili 42:342

Zuhayr narrated to us, Abdullah bin Yazid narrated to us, Haywah narrated to us, Salim bin Ghaylan informed us that al-Walid bin 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 Prophet of Allah, may Allah bless him and grant him peace, saying: "Do not keep company except with a believer, and let no one eat your food except a God-fearing person."