Musannaf Ibn Abi Shayba 26:414

Muhammad ibn Fudayl narrated to us, from Bassam, from Fudayl, from Ibrahim, who said: A Christian does not inherit from a Muslim, nor does a Muslim inherit from a Christian. This is the opinion of Ali and Zayd. As for Abdullah ibn Mas’ud, he used to judge that they (the non-Muslim relatives) are blocked (from inheritance) but they do not cause others to be blocked (from inheritance).