Sahih Muslim 1802 a
It has been narrated on the authority of Salama b. al-Akwa' who said:
We marched upon Khaibar with the Messenger of Allah (ﷺ). We journeyed during the night. One of the people said to (my brother) 'Amir b. al-Akwa': Won't you recite to us some of your verses? Amir was a poet. So he began to chant his verses to urge the camels, reciting: 
O God, if Thou hadst not guided us 
We would have neither been guided rightly nor practised charity, 
Nor offered prayers. 
We wish to lay down our lives for Thee; so forgive Thou our lapses, 
And keep us steadfast when we encounter (our enemies). 
Bestow upon us peace and tranquillity. 
Behold, when with a cry they called upon us to help. 
The Messenger of Allah (ﷺ) said: Who is this driver (of the camels)? They said: It is 'Amir. He said: God will show mercy to him. A man said: Martyrdom is reserved for him. Messenger of Allah, would that you had allowed us to benefit ourselves from his life. (The narrator says): We reached Khaibar and besieged them, and (we continued the siege) until extreme hunger afflicted us. Then the Messenger of Allah (ﷺ) said: Behold, God has conquered it for you. When it was evening of the day on which the city was conquered. the Muslims lit many fires. The Messenger of Allah (ﷺ) said: What are these fires? And what are they cooking? They said: They are cooking meat. He asked. Which meat? They said: That of domestic asses. He said: Let them throw it away and break the pots (in which it is being cooked). A man said: Or should they throw it away and wash the pots? He said: They may do that. When the people drew themselves up in battle array 'Amir caught hold of his sword that was rather short He drove a Jew before him to strike him with it. (As he struck him), his sword recoiled and struck his own knee, and 'Amir died of the wound. When the people returned (after the conquest of Kliaibar) and he (Salama) had caught hold of my hand, and said: The Messenger of Allah (ﷺ) saw that I was silent (and dejected) ; he said: What's the matter with thee? I said to him: My father and my mother be thy ransom, people presume that 'Amir's sacrifice has been in vain. He asked: Who has said that? I said: So and so and Usaid b. Hudair al-Ansari. He said: Who has said that has lied. For him (for 'Amir) there is a double reward. (He indicated this by putting two of his fingers together.) He was a devotee of God and a warrior fighting for His cause. There will be hardly any Arab who can fight as bravely as he did. Qutaiba has differed in a few words.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، وَمُحَمَّدُ بْنُ عَبَّادٍ، - وَاللَّفْظُ لاِبْنِ عَبَّادٍ - قَالاَ حَدَّثَنَا حَاتِمٌ، - وَهُوَ ابْنُ إِسْمَاعِيلَ - عَنْ يَزِيدَ بْنِ أَبِي عُبَيْدٍ، مَوْلَى سَلَمَةَ بْنِ الأَكْوَعِ عَنْ سَلَمَةَ بْنِ الأَكْوَعِ، قَالَ خَرَجْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم إِلَى خَيْبَرَ فَتَسَيَّرْنَا لَيْلاً فَقَالَ رَجُلٌ مِنَ الْقَوْمِ لِعَامِرِ بْنِ الأَكْوَعِ أَلاَ تُسْمِعُنَا مِنْ هُنَيْهَاتِكَ وَكَانَ عَامِرٌ رَجُلاً شَاعِرًا فَنَزَلَ يَحْدُو بِالْقَوْمِ يَقُولُ اللَّهُمَّ لَوْلاَ أَنْتَ مَا اهْتَدَيْنَا وَلاَ تَصَدَّقْنَا وَلاَ صَلَّيْنَا فَاغْفِرْ فِدَاءً لَكَ مَا اقْتَفَيْنَا وَثَبِّتِ الأَقْدَامَ إِنْ لاَقَيْنَا وَأَلْقِيَنْ سَكِينَةً عَلَيْنَا إِنَّا إِذَا صِيحَ بِنَا أَتَيْنَا وَبِالصِّيَاحِ عَوَّلُوا عَلَيْنَا فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ مَنْ هَذَا السَّائِقُ ‏"‏ ‏.‏ قَالُوا عَامِرٌ ‏.‏ قَالَ ‏"‏ يَرْحَمُهُ اللَّهُ ‏"‏ ‏.‏ فَقَالَ رَجُلٌ مِنَ الْقَوْمِ وَجَبَتْ يَا رَسُولَ اللَّهِ لَوْلاَ أَمْتَعْتَنَا بِهِ ‏.‏ قَالَ فَأَتَيْنَا خَيْبَرَ فَحَصَرْنَاهُمْ حَتَّى أَصَابَتْنَا مَخْمَصَةٌ شَدِيدَةٌ ثُمَّ قَالَ ‏"‏ إِنَّ اللَّهَ فَتَحَهَا عَلَيْكُمْ ‏"‏ ‏.‏ قَالَ فَلَمَّا أَمْسَى النَّاسُ مَسَاءَ الْيَوْمِ الَّذِي فُتِحَتْ عَلَيْهِمْ أَوْقَدُوا نِيرَانًا كَثِيرَةً فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ مَا هَذِهِ النِّيرَانُ عَلَى أَىِّ شَىْءٍ تُوقِدُونَ ‏"‏ ‏.‏ فَقَالُوا عَلَى لَحْمٍ ‏.‏ قَالَ ‏"‏ أَىُّ لَحْمٍ ‏"‏ ‏.‏ قَالُوا لَحْمُ حُمُرِ الإِنْسِيَّةِ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أَهْرِيقُوهَا وَاكْسِرُوهَا ‏"‏ ‏.‏ فَقَالَ رَجُلٌ أَوْ يُهَرِيقُوهَا وَيَغْسِلُوهَا فَقَالَ ‏"‏ أَوْ ذَاكَ ‏"‏ ‏.‏ قَالَ فَلَمَّا تَصَافَّ الْقَوْمُ كَانَ سَيْفُ عَامِرٍ فِيهِ قِصَرٌ فَتَنَاوَلَ بِهِ سَاقَ يَهُودِيٍّ لِيَضْرِبَهُ وَيَرْجِعُ ذُبَابُ سَيْفِهِ فَأَصَابَ رُكْبَةَ عَامِرٍ فَمَاتَ مِنْهُ قَالَ فَلَمَّا قَفَلُوا قَالَ سَلَمَةُ وَهُوَ آخِذٌ بِيَدِي قَالَ فَلَمَّا رَآنِي رَسُولُ اللَّهِ صلى الله عليه وسلم سَاكِتًا قَالَ ‏"‏ مَا لَكَ ‏"‏ ‏.‏ قُلْتُ لَهُ فِدَاكَ أَبِي وَأُمِّي زَعَمُوا أَنَّ عَامِرًا حَبِطَ عَمَلُهُ قَالَ ‏"‏ مَنْ قَالَهُ ‏"‏ ‏.‏ قُلْتُ فُلاَنٌ وَفُلاَنٌ وَأُسَيْدُ بْنُ حُضَيْرٍ الأَنْصَارِيُّ فَقَالَ ‏"‏ كَذَبَ مَنْ قَالَهُ إِنَّ لَهُ لأَجْرَيْنِ ‏"‏ ‏.‏ وَجَمَعَ بَيْنَ إِصْبَعَيْهِ ‏"‏ إِنَّهُ لَجَاهِدٌ مُجَاهِدٌ قَلَّ عَرَبِيٌّ مَشَى بِهَا مِثْلَهُ ‏"‏ ‏.‏ وَخَالَفَ قُتَيْبَةُ مُحَمَّدًا فِي الْحَدِيثِ فِي حَرْفَيْنِ وَفِي رِوَايَةِ ابْنِ عَبَّادٍ وَأَلْقِ سَكِينَةً عَلَيْنَا ‏.‏