(120) باب فِي الرَّجُلِ يَنْتَمِي إِلَى غَيْرِ مَوَالِيهِ
Abu Hurairah reported the Prophet (May peace be upon him) as saying :
if a man becomes the client of any people without the permission of his patrons (i.e. those who have freed him), on him will be the curse of Allah, of angels and of all people; no obligatory or supererogatory worship will be accepted from him.
Reference: Sunan Abi Dawud 5114
In-book reference: Book 43, Hadith 342
English translation: Book 42, Hadith 5095