Mercy of Allah

Jundub reported that Allaah’s Messenger (sallAllaahu alayhi wa sallam) stated that a person said: Allaah would not forgive such and such (person). Thereupon Allaah the Exalted and Glorious, said: Who is he who adjures about Me that I would not grant pardon to so and so; I have granted pardon to so and so and blotted out his deeds (who took an oath that I would not grant pardon to him). (Muslim, 6350)