Abu Waail reported,

Sahl bin Hunayf stood up on the day of Siffin and said, "People, suspect your own opinions. We were with the Messenger of Allah ﷺ on the day of Hudaybiyah. Had we seen a fight to be waged, we would have fought." This was during the truce that took place between the Messenger of Allah ﷺ and the polytheists.Umar bin Khattab came and approached the Messenger of Allah ﷺ and said, "Messenger of Allah, are we not upon the truth and they upon falsehood?"He replied, "Yes, indeed."Umar asked, "Are not our slain in Paradise and their slain in the Fire?"He replied, "Yes, indeed."Umar said, "Then why should we accept what is degrading in our religion and turn back when Allah has not yet judged between us and them?"He answered, "Son of Khattab, I am the Messenger of Allah ﷺ, and Allah will never abandon me."Umar departed, unable to contain his anger. He went to Abu Bakr and said, "Abu Bakr, are we not upon the truth and they upon falsehood?"Abu Bakr replied, "Yes, indeed."Umar asked, "Are not our slain in Paradise and their slain in the Fire?"Abu Bakr replied, "Yes, indeed."Umar said, "Then why should we accept what is degrading in our religion and turn back when Allah has not yet judged between us and them?"Abu Bakr answered, "Son of Khattab, he is the Messenger of Allah ﷺ, and Allah will never abandon him."Then the Quran was revealed to the Messenger of Allah ﷺ announcing the victory. He sent for Umar and recited it to him.Umar said, "Messenger of Allah, is this truly a victory?"He replied, "Yes."So Umar was satisfied and returned content.

عن أبي وائل قال

قام سهل بن حنيف يوم صفين فقال: أيها الناس! اتهموا أنفسكم. لقد كنا مع رسول الله ﷺ يوم الحديبية. ولو نرى قتالا لقاتلنا. وذلك في الصلح الذي كان بين رسول الله ﷺ بين المشركين. فجاء عمر بن الخطاب. فأتى رسول الله ﷺ فقال: يارسول الله! ألسنا على حق وهم على باطل؟ قال: بلى قال: أليس قتلانا في الجنة وقتلاهم في النار؟ قال: بلى قال: ففيم نعطي الدنية في ديننا، ونرجع ولما يحكم الله بيننا وبينهم؟ فقال: يا ابن الخطاب! إني رسول الله ﷺ ولن يضيعني الله أبدا قال: فانطلق عمر فلم يصبر متغيظا. فأتى أبا بكر فقال: يا أبا بكر! ألسنا على حق وهم على باطل؟ قال: بلى قال: أليس قتلانا في الجنة وقتلاهم في النار؟ قال: بلى قال: فعلام نعطي الدنية في ديننا، ونرجع ولما يحكم الله بيننا وبينهم؟ فقال: يا ابن الخطاب! إنه رسول الله ﷺ ولن يضيعه الله أبدا. قال: فنزل القرآن على رسول الله ﷺ بالفتح. فأرسل إلى عمر فأقرأه إياه. فقال: يا رسول الله! أو فتح هو؟ قال: نعم فطابت نفسه ورجع.