Musannaf Ibn Abi Shayba 26:367

Shababa narrated to us, from Ibn Abi Dhi'b, from al-Zuhri, from Sa'id ibn al-Musayyib, who said: The Prophet (may Allah bless him and grant him peace) decreed that a killer does not inherit anything from the blood money (diyah) of his relative whom he killed, whether intentionally or by mistake. Al-Zuhri said: The killer does not inherit anything from the blood money of the one he killed, even if it were a child or a parent. However, he does inherit from his wealth, because Allah knew that people would kill one another, and it is not appropriate for anyone to sever the inheritances that He has ordained.