Musnad Abu Ya'la al-Mawsili 209:3

Ghassan ibn al-Rabi' narrated to us, from Hammad ibn Salamah, from Hisham ibn 'Urwah, from 'Urwah, from Zaynab bint Umm Salamah, from Umm Salamah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "You bring your disputes to me, and I am only a human being. It may be that some of you are more eloquent in their argument than others. So, whoever I judge in his favor regarding his brother's right, let him not take it, for I am only cutting out for him a piece of the Fire."