Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Dhahhak that two men brought their dispute to Hazrat Umar (may Allah be pleased with him). Both of them demanded testimony from him. Hazrat Umar (may Allah be pleased with him) said to them: If you wish, I will give testimony but then I will not judge, and if you wish that I judge, then I will not give testimony.

It is narrated from Hazrat Abdul A'la that a woman came to Hazrat Shurayh, may Allah have mercy on him, with one witness. He said, "Bring one more witness." The woman said, "You are my witness." He took an oath from the woman and gave a verdict in her favor.

Hazrat Sha’bi (may Allah have mercy on him) said: I do not combine both roles, that I become both the judge and the witness.

Hazrat Sha’bi (may Allah have mercy on him) was asked about a case where a person’s wealth was owed by another. He presented two witnesses. Then he wanted to have judgment passed by one of the two witnesses. After that, another person came who had one witness with him. He said to Hazrat Shurayh (may Allah have mercy on him): “Bear witness in my favor.” Hazrat Shurayh (may Allah have mercy on him) replied: “Call the Amir so that I may bear witness (meaning, then I will not be the judge or the decision-maker).”