Sayyiduna al-Miqdam bin Ma'dikarib (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever leaves behind a burden (debt or helpless dependants), it is the responsibility of Allah and His Messenger - or he said: it is our responsibility - and whoever leaves wealth, it belongs to his heirs. I am the heir of the one who has no heir: I inherit his wealth and free his captive (that is, pay his blood money and the like). And the maternal uncle is the mawla (guardian) of the one who has no mawla: he inherits his wealth and frees his captive."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17759