(39) باب النَّهْىِ عَنْ تَقْنِيطِ الإِنْسَانِ، مِنْ رَحْمَةِ اللَّهِ تَعَالَى
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).
Reference: Sahih Muslim 2621
In-book reference: Book 45, Hadith 178
USC-MSA web (English) reference(deprecated numbering scheme): Book 32, Hadith 6350