Sahih Bukhari Volume 009, Book 089, Hadith Number 281.
Narrated By Um Salama : Allah's Apostle said, "I am only a human being, and you people (opponents) come to me with your cases; and it may be that one of you can present his case eloquently in a more convincing way than the other, and I give my verdict according to what I hear. So if ever I judge (by error) and give the right of a brother to his other (brother) then he (the latter) should not take it, for I am giving him only a piece of Fire." (See Hadith No. 638, Vol. 3).