(34) باب الْوَلَدِ لِلْفِرَاشِ
'Amr b. Shu'aib on his father's authority said that his grandfather reported:
A man got up and said: Messenger of Allah, so-and-so is my son; I had illicit intercourse with his mother in the pre-Islamic period. The Messenger of Allah (ﷺ) 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.
Reference: Sunan Abi Dawud 2274
In-book reference: Book 13, Hadith 100
English translation: Book 12, Hadith 2267