Sunan of Abu Dawood Book 41, Hadith 4524

حَدَّثَنَا الْحَسَنُ بْنُ عَلِيِّ بْنِ رَاشِدٍ، أَخْبَرَنَا هُشَيْمٌ، عَنْ أَبِي حَيَّانَ التَّيْمِيِّ، حَدَّثَنَا عَبَايَةُ بْنُ رِفَاعَةَ، عَنْ رَافِعِ بْنِ خَدِيجٍ، قَالَ أَصْبَحَ رَجُلٌ مِنَ الأَنْصَارِ مَقْتُولاً بِخَيْبَرَ فَانْطَلَقَ أَوْلِيَاؤُهُ إِلَى النَّبِيِّ صلى الله عليه وسلم فَذَكَرُوا ذَلِكَ لَهُ فَقَالَ ‏"‏ لَكُمْ شَاهِدَانِ يَشْهَدَانِ عَلَى قَتْلِ صَاحِبِكُمْ ‏"‏ ‏.‏ قَالُوا يَا رَسُولَ اللَّهِ لَمْ يَكُنْ ثَمَّ أَحَدٌ مِنَ الْمُسْلِمِينَ وَإِنَّمَا هُمْ يَهُودُ وَقَدْ يَجْتَرِئُونَ عَلَى أَعْظَمَ مِنْ هَذَا ‏.‏ قَالَ ‏"‏ فَاخْتَارُوا مِنْهُمْ خَمْسِينَ فَاسْتَحْلِفُوهُمْ ‏"‏ ‏.‏ فَأَبَوْا فَوَدَاهُ النَّبِيُّ صلى الله عليه وسلم مِنْ عِنْدِهِ ‏.‏

Narrated Rafi' ibn Khadij: A man of the Ansar was killed at Khaybar and his relatives went to the Prophet (ﷺ) and mentioned that to him. He asked: Have you two witnesses who can testify to the murderer of your friend? They replied: Messenger of Allah! there was not a single Muslim present, but only Jews who sometimes have the audacity to do even greater crimes than this. He said: Then choose fifty of them and demand that they take an oath; but they refused and the Prophet (ﷺ) paid the blood-wit himself