Jundub reported that Allah's Messenger (ﷺ) stated that a person said:Allah would not forgive such and such (person). Thereupon Allah 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)

English translation · Sahih Muslim