Musnad Ahmad 323
It was narrated that Abu Unma mah bin Sahl said:
‘Umar wrote to AbuʼUbaidah bin al-Jarrah [saying]: Teach your children swimming and teach your fighters archery. After that they used to practise archery frequently, then a stray arrow came and killed a boy, and no one knew where it came from; he was under the care of his maternal uncle. Abu `Ubaidah wrote to `Umar about that [asking]: To whom should I pay his diyah? ‘Umar wrote back telling him that the Messenger of Allah (ﷺ) used to say: “Allah and His Messenger are the mawla (guardian) of the one who has no mawla, and the maternal uncle is the heir of the one who has no heir.”
حَدَّثَنَا يَحْيَى بْنُ آدَمَ، حَدَّثَنَا سُفْيَانُ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ عَيَّاشٍ، عَنْ حَكِيمِ بْنِ حَكِيمٍ، عَنْ أَبِي أُمَامَةَ بْنِ سَهْلٍ، قَالَ كَتَبَ عُمَرُ رَضِيَ اللَّهُ عَنْهُ إِلَى أَبِي عُبَيْدَةَ بْنِ الْجَرَّاحِ أَنْ عَلِّمُوا غِلْمَانَكُمْ الْعَوْمَ وَمُقَاتِلَتَكُمْ الرَّمْيَ فَكَانُوا يَخْتَلِفُونَ إِلَى الْأَغْرَاضِ فَجَاءَ سَهْمٌ غَرْبٌ إِلَى غُلَامٍ فَقَتَلَهُ فَلَمْ يُوجَدْ لَهُ أَصْلٌ وَكَانَ فِي حَجْرِ خَالٍ لَهُ فَكَتَبَ فِيهِ أَبُو عُبَيْدَةَ إِلَى عُمَرَ رَضِيَ اللَّهُ عَنْهُ إِلَى مَنْ أَدْفَعُ عَقْلَهُ فَكَتَبَ إِلَيْهِ عُمَرُ رَضِيَ اللَّهُ عَنْهُ إِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يَقُولُ اللَّهُ وَرَسُولُهُ مَوْلَى مَنْ لَا مَوْلَى لَهُ وَالْخَالُ وَارِثُ مَنْ لَا وَارِثَ لَهُ‏.‏