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).  

أَنَّ رَسُولَ اللَّهِ ﷺ حَدَّثَ أَنَّ رَجُلاً قَالَ وَاللَّهِ لاَ يَغْفِرُ اللَّهُ لِفُلاَنٍ وَإِنَّ اللَّهَ تَعَالَى قَالَ مَنْ ذَا الَّذِي يَتَأَلَّى عَلَىَّ أَنْ لاَ أَغْفِرَ لِفُلاَنٍ فَإِنِّي قَدْ غَفَرْتُ لِفُلاَنٍ وَأَحْبَطْتُ عَمَلَكَ أَوْ كَمَا قَالَ  

[Machine] The Messenger of Allah ﷺ said, "A man said, 'By Allah, Allah will not forgive so-and-so.' Allah, the Blessed and Exalted, then said, 'I have indeed forgiven so-and-so and nullified your deeds.'"  

قَالَ رَسُولُ اللَّهِ ﷺ «قَالَ رَجُلٌ وَاللَّهِ لَا يَغْفِرُ اللَّهُ لِفُلَانٍ فَقَالَ اللَّهُ تَبَارَكَ وَتَعَالَى قَدْ غَفَرْتُ لِفُلَانٍ وَأَحْبَطْتُ عَمَلَكَ»  

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). (Using translation from Muslim 2621)   

قَالَ رَسُولُ اللهِ ﷺ قَالَ رَجُلٌ وَاللهِ لَا يَغْفِرُ اللهُ لِفُلَانٍ فَقَالَ اللهُ ﷻ مَنْ ذَا الَّذِي يَتَأَلَّى عَلَيَّ أَنْ لَا أَغْفِرَ لِفُلَانٍ فَإِنِّي قَدْ غَفَرْتُ لِفُلَانٍ وَأَحْبَطْتُ عَمَلَكَ  

[Machine] A man said in reference to someone who has passed away, "By Allah, Allah will never forgive so-and-so." So Allah revealed to a prophet in his time to inform him that He has indeed forgiven him and nullified your deeds against him.  

قَالَ رَجُلٌ فِيمَنْ مَضَى وَاللَّهِ لَا يَغْفِرُ اللَّهُ لِفُلَانٍ أَبَدًا فَأَوْحَى اللَّهُ ﷻ إِلَى نَبِيٍّ فِي زَمَانِهِ أَنْ أَخْبِرْهُ أَنِّي قَدْ غَفَرْتُ لَهُ وَأَحْبَطْتُ عَمَلَكَ عَلَى تَأَلِّيكَ