Sahih Muslim Book 10, Hadith Number 3779.
Chapter : Prohibition of the sale of excess water in the barren lands, and preventing people to use it, and hiring a camel to cover a she-camel.
‘Aisha (Allah be pleased with her) reported: Allah’s Messenger (may peace be upon him) heard the voices of altercation of two disputants at the door; both the voices were quite loud. The one demanded some remission and desired that the other one should show leniency to him, whereupon the (other one) was saying: By Allah will not do that. Then there came Allah’s Messenger (may peace be upon him) to them and said: Where is he who swears by Allah that he would not do good? He said: Messenger of Allah, it is I. He may do as he desires.