‘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.”