Sahih Muslim Book 1, Hadith Number 118.

Chapter : The condition of the Faith of one who knowingly denies his true fatherhood.

It is reported on the authority of Abu Dharr that he heard the Messenger of Allah (may peace and blessings be upon him) saying: No person who claimed knowingly anyone else as his father besides(his own)committed nothing but infidelity, and he who made a claim of anything, which (in fact) did not belong to him, is not amongst us; he should make his abode in Fire, and he who labelled anyone with unbelief or called him the enemy of Allah, and he was in fact not so, it rebounded on him.