Musannaf Ibn Abi Shayba 13:2677

Abu Bakr narrated to us, he said: Waki' narrated to us, he said: Hanzala narrated to us, from Tawus, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Al-Ruqba is not permissible. So whoever is given a Ruqba, it is subject to the laws of inheritance."