It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Whoever claims descent from someone other than his father, or takes as patrons (wala') people other than his freers, upon him is the curse of Allah, the angels and all the people."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12422