It is narrated from Sayyiduna al-Miqdam (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever leaves a debt or helpless dependants, it is my responsibility, and whoever leaves wealth, it belongs to his heir. I am the mawla of the one who has no mawla: I free his captive (that is, pay his blood money and the like) and inherit his wealth. And the maternal uncle is the mawla of the one who has no mawla: he frees his captive and inherits his wealth."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17761