A man who cites the judge or governor as a witness

It is narrated from al-Dahhak that two men took their dispute to Sayyiduna Umar (may Allah be pleased with him), and both of them asked him for his testimony. Sayyiduna Umar (may Allah be pleased with him) said to them: If you wish, I will testify, but then I will not judge; and if you wish me to judge, then I will not testify.

It is narrated from Abd al-A'la that a woman came to Shurayh (may Allah have mercy on him) with one witness. He said: Bring one more witness. The woman said: You are my witness. He had the woman take an oath and ruled in her favour.

Al-Sha'bi (may Allah have mercy on him) said: I do not combine the two, being both a judge and a witness.

Al-Sha'bi (may Allah have mercy on him) was asked about a man whose money was owed by another man. He presented two witnesses, and then sought a judgment from one of the two witnesses? Al-Sha'bi (may Allah have mercy on him) said: A man came to Shurayh (may Allah have mercy on him) with a dispute while I was sitting with him. Then the other man came with one witness, and he said to Shurayh (may Allah have mercy on him): You testify in my favour. Shurayh (may Allah have mercy on him) said: Go to the Amir, so that I may testify (that is, then I will not be the judge or arbiter).