Narrated Abu Wail:

We were in Siffin and Sahl bin Hunaif got up and said, "O people! Blame yourselves! We were with the Prophet on the day of Hudaibiya, and if we had been called to fight, we would have fought. But 'Umar bin Al Khatab came and said, 'O Allah's Apostle! Aren't we in the right and our opponents in the wrongs' Allah's Apostle ﷺ said, 'Yes.' 'Umar said, 'Aren't our killed persons in Paradise and their's in Hell?' He said, 'Yes.' 'Umar said, 'Then why should we accept hard terms in matters concerning our religion? Shall we return before Allah judges between us and them?' Allah's Apostle ﷺ said, 'O Ibn Al-Khattab! I am the Apostle of Allah and Allah will never degrade me. Then 'Umar went to Abu Bakr and told him the same as he had told the Prophet. On that Abu Bakr said (to 'Umar). 'He is the Apostle of Allah and Allah will never degrade him.' Then Surat-al-Fath (i.e. Victory) was revealed and Allah's Apostle recited it to the end in front of 'Umar. On that 'Umar asked, 'O Allah's Apostle! Was it (i.e. the Hudaibiya Treaty) a victory?' Allah's Apostle ﷺ said, "Yes"

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ، حَدَّثَنَا يَحْيَى بْنُ آدَمَ، حَدَّثَنَا يَزِيدُ بْنُ عَبْدِ الْعَزِيزِ، عَنْ أَبِيهِ، حَدَّثَنَا حَبِيبُ بْنُ أَبِي ثَابِتٍ، قَالَ حَدَّثَنِي أَبُو وَائِلٍ، قَالَ كُنَّا بِصِفِّينَ فَقَامَ سَهْلُ بْنُ حُنَيْفٍ فَقَالَ أَيُّهَا النَّاسُ اتَّهِمُوا أَنْفُسَكُمْ فَإِنَّا كُنَّا مَعَ رَسُولِ اللَّهِ ﷺ يَوْمَ الْحُدَيْبِيَةِ، وَلَوْ نَرَى قِتَالاً لَقَاتَلْنَا، فَجَاءَ عُمَرُ بْنُ الْخَطَّابِ فَقَالَ يَا رَسُولَ اللَّهِ، أَلَسْنَا عَلَى الْحَقِّ وَهُمْ عَلَى الْبَاطِلِ فَقَالَ " بَلَى ". فَقَالَ أَلَيْسَ قَتْلاَنَا فِي الْجَنَّةِ وَقَتْلاَهُمْ فِي النَّارِ قَالَ " بَلَى ". قَالَ فَعَلَى مَا نُعْطِي الدَّنِيَّةَ فِي دِينِنَا أَنَرْجِعُ وَلَمَّا يَحْكُمِ اللَّهُ بَيْنَنَا وَبَيْنَهُمْ فَقَالَ " ابْنَ الْخَطَّابِ، إِنِّي رَسُولُ اللَّهِ، وَلَنْ يُضَيِّعَنِي اللَّهُ أَبَدًا ". فَانْطَلَقَ عُمَرُ إِلَى أَبِي بَكْرٍ فَقَالَ لَهُ مِثْلَ مَا قَالَ لِلنَّبِيِّ ﷺ فَقَالَ إِنَّهُ رَسُولُ اللَّهِ، وَلَنْ يُضَيِّعَهُ اللَّهُ أَبَدًا. فَنَزَلَتْ سُورَةُ الْفَتْحِ، فَقَرَأَهَا رَسُولُ اللَّهِ ﷺ عَلَى عُمَرَ إِلَى آخِرِهَا. فَقَالَ عُمَرُ يَا رَسُولَ اللَّهِ، أَوَفَتْحٌ هُوَ قَالَ " نَعَمْ ".