Sunan Abi Dawud 5114
سنن أبي داود#5114SahihAbu 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Muslim (1508)
In-book reference: 43:342