A man who decided someone else was finished
He said Allah would not forgive so-and-so. He was answered directly.
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
Allah said: who is this swearing by Me that I will not forgive so-and-so? I have forgiven him, and I have cancelled your deeds.
The one who condemned lost everything. The one condemned was forgiven. It is the clearest warning in the collections against writing anyone off.
The full narration
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)
Source
Ṣaḥīḥ Muslim · 6681
- Agreed upon as authentic (al-Bukhārī / Muslim)