Musannaf Ibn Abi Shayba 36:313

Abdullah bin Numayr narrated to us, he said: Abd al-Aziz bin Siyah narrated to us, he said: Habib bin Abi Thabit narrated to us, from Abu Wa'il, from Sahl bin Hunayf, who said: We were with the Messenger of Allah, may Allah bless him and grant him peace, and if we had seen fighting, we would have fought. That was during the peace treaty that was between the Messenger of Allah, may Allah bless him and grant him peace, and the polytheists. Umar bin al-Khattab came and went to the Messenger of Allah, may Allah bless him and grant him peace, and said: "O Messenger of Allah, are we not upon the truth and they upon falsehood?" He said: "Yes." He said: "Are our killed not in Paradise and their killed in the Fire?" He said: "Yes." He said: "Then why do we accept humiliation and return, while Allah has not yet judged between us and them?" He said: "O son of al-Khattab, I am the Messenger of Allah, and Allah will never let me go to waste." Umar departed, unable to contain his rage, until he came to Abu Bakr and said: "O Abu Bakr, are we not upon the truth and they upon falsehood?" He said: "Yes." He said: "Are our killed not in Paradise and their killed in the Fire?" He said: "Yes." He said: "Then why do we accept humiliation in our religion and return, while Allah has not yet judged between us and them?" He said: "O son of al-Khattab, he is the Messenger of Allah, and Allah will never let him go to waste." He said: Then the Quran was revealed to the Messenger of Allah, may Allah bless him and grant him peace, regarding the victory. So he sent for Umar and recited it to him. He said: "O Messenger of Allah, is it a victory?" He said: "Yes." So his soul became at ease, and he returned.