Musannaf Ibn Abi Shayba 26:358

Waki’ narrated to us, he said: Sufyan narrated to us, from Musa ibn Abi Kathir, he said: I asked Sa’id ibn al-Musayyib about the inheritance of the apostate: "Is it joined [to the estate of the Muslims]?" He said: "It is not joined." I said: "Do his children inherit from him?" He said: "We inherit from them, and they do not inherit from us."