Musnad Abu Ya'la al-Mawsili 152:198

Muhammad narrated to me, Uthman ibn Umar narrated to us, Fitr ibn Khalifah narrated to us, from Mansur, from Salim ibn Abi al-Ja'd, from Masruq, who said: I was sitting with Abdullah, and a man said to him, "What is *al-suht* (ill-gotten gain)?" He said, "Bribery." He said, "In judgment?" He said, "That is disbelief." Then he recited: "And whoever does not judge by what Allah has revealed, then it is those who are the disbelievers."