Musannaf Ibn Abi Shaybah 24489 — What a judge should begin with

It is narrated from Muhammad bin Ubaydullah that when the Prophet (peace and blessings be upon him) sent Sayyiduna Mu'adh (may Allah be pleased with him) to Yemen as a judge, he said: "O Mu'adh! How will you judge?" Sayyiduna Mu'adh said: "I will judge according to the Book of Allah." He (peace and blessings be upon him) said: "What if a matter comes up that is not in the Qur'an?" Sayyiduna Mu'adh said: "I will judge according to the judgment of the Messenger (peace and blessings be upon him)." He (peace and blessings be upon him) said: "What if a matter comes up that is not in the Qur'an, the Prophet (peace and blessings be upon him) has not judged on it, and there is no judgment on it from the righteous people of earlier times either?" Sayyiduna Mu'adh (may Allah be pleased with him) said: "I will reach the correct judgment through my effort and opinion." The Prophet (peace and blessings be upon him) said: "All praise is for Allah, who has granted the envoy of the Messenger (peace and blessings be upon him) the ability to judge in accordance with what pleases the Messenger of Allah (peace and blessings be upon him)."