Sunan Abi Dawud 3605
Ash-Sha'bi said:
A Muslim was about to die at Daquqa', but he did not find any Muslim to call him for witness to his will. So he called two men of the people of the Book for witness. Then they came to Kufah, and approaching AbuMusa al-Ash'ari they informed him (about his) will. They brought his inheritance and will. Al-Ash'ari said: This is an incident (like) which happened in the time of the Messenger of Allah (ﷺ) and never occurred after him. So he made them to swear by Allah after the afternoon prayer to the effect that they had not misappropriated, nor  told a lie, nor changed, nor concealed, nor altered, and that it was the will of the man and his inheritance. He then executed their witness.
حَدَّثَنَا زِيَادُ بْنُ أَيُّوبَ، حَدَّثَنَا هُشَيْمٌ، أَخْبَرَنَا زَكَرِيَّا، عَنِ الشَّعْبِيِّ، أَنَّ رَجُلاً، مِنَ الْمُسْلِمِينَ حَضَرَتْهُ الْوَفَاةُ بِدَقُوقَاءَ هَذِهِ وَلَمْ يَجِدْ أَحَدًا مِنَ الْمُسْلِمِينَ يُشْهِدُهُ عَلَى وَصِيَّتِهِ فَأَشْهَدَ رَجُلَيْنِ مِنْ أَهْلِ الْكِتَابِ فَقَدِمَا الْكُوفَةَ فَأَتَيَا أَبَا مُوسَى الأَشْعَرِيَّ فَأَخْبَرَاهُ وَقَدِمَا بِتَرِكَتِهِ وَوَصِيَّتِهِ ‏.‏ فَقَالَ الأَشْعَرِيُّ هَذَا أَمْرٌ لَمْ يَكُنْ بَعْدَ الَّذِي كَانَ فِي عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏ فَأَحْلَفَهُمَا بَعْدَ الْعَصْرِ بِاللَّهِ مَا خَانَا وَلاَ كَذِبَا وَلاَ بَدَّلاَ وَلاَ كَتَمَا وَلاَ غَيَّرَا وَإِنَّهَا لَوَصِيَّةُ الرَّجُلِ وَتَرِكَتُهُ فَأَمْضَى شَهَادَتَهُمَا ‏.‏