Musannaf Ibn Abi Shayba 13:3000

Abu Bakr narrated to us, he said: Jarir narrated to us, from Qabus, from his father, from Ibn Abbas, regarding the saying of the Exalted: "O you who have believed, be persistently standing firm in justice." He said: Two men sit before the judge, and the judge shows inclination and turning away toward one of the two men to the exclusion of the other.