Musannaf Ibn Abi Shaybah

Fudayl Ibrahim narrates about that Muslim woman who leaves behind a Muslim husband and Muslim maternal brothers, and she has a Christian or Jewish or disbelieving son; that her husband receives half the estate, that is, three shares, and her maternal brothers receive one third of the estate, that is, two shares, and the remaining estate, according to the command of Hazrat Ali (may Allah be pleased with him) and Zaid (may Allah be pleased with him), is for the 'asaba (agnatic heirs). And a Jewish or Christian man cannot inherit from a Muslim. And in this matter, Hazrat Abdullah (may Allah be pleased with him) decided that the husband receives one fourth of the estate because she has a disbelieving son, and in the opinion of Hazrat Abdullah (may Allah be pleased with him), a disbelieving relative can reduce the shares of others but cannot inherit himself. And in the opinion of Hazrat Ali (may Allah be pleased with him), they neither reduce the shares of others nor inherit themselves. Hazrat Abu Bakr says that this issue, according to the opinion of Hazrat Ali (may Allah be pleased with him) and Zaid (may Allah be pleased with him), will be resolved from six shares, and according to the opinion of Hazrat Abdullah bin Mas'ud (may Allah be pleased with him), from four shares.