Sayyiduna Abu Umamah bin Sahl bin Hunayf (may Allah be pleased with him) narrates that Sayyiduna Umar (may Allah be pleased with him) wrote to Sayyiduna Abu Ubaidah bin Jarrah (may Allah be pleased with him) instructing him to teach swimming to his sons and archery to his warriors. The narrator says: They (the people) were disputing over the spoils of war when an unknown arrow came and killed a boy who was being raised by his maternal uncle, and there was no trace of his father. Sayyiduna Abu Ubaidah (may Allah be pleased with him) wrote to Sayyiduna Umar (may Allah be pleased with him) asking to whom he should hand over the blood money. So Sayyiduna Umar (may Allah be pleased with him) wrote back that the Messenger of Allah (peace and blessings be upon him) used to say: Whoever has no mawla, Allah and His Messenger are his mawla, and whoever has no heir, the maternal uncle is his heir.