Anas bin Malik reported,

He was asked, "Did you go on a military expedition with the Prophet of Allah ﷺ?"He replied, "Yes. I fought alongside him on the Day of Hunayn. The polytheists came out in great numbers and charged at us until we saw our own cavalry pushed behind our backs. Among the polytheists was a man who kept attacking us, crushing and overwhelming us. When the Prophet of Allah ﷺ saw this, he dismounted, and Allah routed them, so they turned and fled. The Prophet of Allah stood up when he saw the victory, and the captives began to be brought to him one by one to pledge allegiance to him on Islam.A man from among the companions of the Messenger of Allah ﷺ said, 'I have made a vow that if the man who was crushing us earlier today is brought, I will strike off his neck.'The Prophet of Allah ﷺ remained silent. Then the man was brought, and when he saw the Prophet of Allah, he said, 'Prophet of Allah, I have repented to Allah. Prophet of Allah, I have repented to Allah.'The Prophet of Allah ﷺ held back and did not take his pledge, so that the other man might fulfill his vow. The man kept looking at the Prophet ﷺ, waiting for him to give the order to kill him, but he was too in awe of the Prophet of Allah ﷺ to kill him on his own. When the Prophet of Allah ﷺ saw that he was doing nothing, he accepted the man's pledge.The man said, 'Prophet of Allah, what about my vow?'He replied, 'I only held back from accepting his pledge all this time so that you might fulfill your vow.'The man said, 'Prophet of Allah, why did you not give me a signal?'He answered, 'It is not fitting for a prophet to give covert signals.'"

عن أنس بن مالك

أنه سئل: هل غزوت مع نبي الله ﷺ؟ قال: نعم، غزوت معه يوم حنين، فخرج المشركون بكثرة، فحملوا علينا، حتى رأينا خيلنا وراء ظهورنا، وفي المشركين رجل يحمل علينا، فيدقنا ويحطمنا، فلما رأى ذلك نبي الله ﷺ نزل فهزمهم الله فولوا، فقام نبي الله حين رأى الفتح، فجعل يجاء بهم أسارى رجلا رجلا، فيبايعونه على الإسلام، فقال رجل من أصحاب رسول الله ﷺ: إن علي نذرا لئن جيء بالرجل الذي كان منذر اليوم يحطمنا لأضربن عنقه. قال: فسكت نبي الله ﷺ، وجيء بالرجل، فلما رأى نبي الله، قال: يا نبي الله، تبت إلى الله، يا نبي الله تبت إلى الله. قال: فأمسك نبي الله ﷺ، فلم يبايعه ليوفي الآخر نذره، قال: فجعل ينظر النبي ﷺ ليأمره بقتله، وجعل يهاب نبي الله ﷺ أن يقتله، فلما رأى نبي الله ﷺ أنه لا يصنع شيئا بايعه. فقال: يا نبي الله نذري؟ قال: لم أمسك عنه منذ اليوم إلا لتوافي نذرك فقال: يا نبي الله! ألا أو مضت إلي؟ فقال: إنه ليس لنبي أن يومض