The Prophet ﷺ said, "I am only a human being, and you bring your disputes to me. Perhaps one of you is more eloquent in presenting his argument than the other, so I rule in his favor based on what I hear. Whoever I grant something from his brother's right, let him not take it, for I am only allotting him a piece of the Fire."
عن النبي ﷺ قال: إنما أنا بشر، وإنكم تختصمون، ولعل بعضكم أن يكون ألحن بحجته من بعض، وأقضي له على نحو ما أسمع، فمن قضيت له من حق أخيه شيئا فلا يأخذ، فإنما أقطع له قطعة من النار.
Bukhari narrated it in the Book of Tricks (6967) and Muslim in the Book of Judgments (1713), both through the route of Hisham bin Urwa, from his father, from Zaynab bint Abu Salama, from Umm Salama, who said, and then she mentioned it. The wording given is that of Bukhari, and Muslim's wording is similar.