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 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 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 said, "Yes"