Sahih al-Bukhari 6503

Zaynab bint Abi Salama related from Umm Salama that the Messenger of Allah, may Allah bless him and grant him peace, said, "I am a human being. Litigants come to me and it may be that one of them are more eloquent than the other and so I suppose that he is telling the truth and give judgement in his favour according to what I hear. If I judge for him any of the right of his brother, then I am only cutting for him a piece of the Fire." XXI. Testimony is given the presence of the judge when he undertakes judgement or before that in favour of the litigant Qadi Shurayh said to someone who asked him to testify, "Go the amir so that I can testify on your behalf." 'Ikrima said that 'Umar asked 'Abdu'r-Rahman ibn 'Awf, "What [would you do] if you saw a man committing a hadd, fornication or theft, and you were amir?" He replied, "Your testimony is the testimony of one Muslim man." [i.e. further witnesses are required.] "You spoke the truth," he said. 'Umar said, "If it were not that people would say, ''Umar has added to the Book of Allah,' I would have written out the verse of stoning with my own hand." Ma'iz admitted to fornication four times in the presence of the Prophet, may Allah bless him and grant him peace, and he commanded that he be stoned. It is not mentioned that the Prophet, may Allah bless him and grant him peace, asked any of those present to testify. Hammad [ibn Abi Sulayman] said, "If he confesses once before the ruler, he is stoned." Al-Hakam said that it must be four times.