Divorce (Kitab Al-Talaq)
Dawud :: Book 12 : Hadith 2267
Narrated Abdullah ibn Amr ibn al-'As:
A man got up and said: Apostle of Allah, so-and-so is my son; I had illicit intercourse with his mother in the pre-Islamic period. The Apostle of Allah (peace_be_upon_him) said: There is no unlawful claiming of paternity in Islam. What was done in pre-Islamic times has been annulled. The child is attributed to the one on whose bed it is born, and the fornicator is deprived of any right.