333.The one who claims descent from someone other than his (real) father, and the slave who attaches himself to someone other than his (real) master, are cursed by Allah, His angels, and the people, Allah will accept neither repentance nor ransom from such person on the Day of Resurrection. (Bukhari, Muslim).
(The Lawful and Prohibited in Islam (arb: Al Halal Wal Haram Fil Islam) by. Yusuf Qaradawi).