‘Umar ibn al-Khattāb (may Allah be pleased with him) said: "If a man acknowledges his paternity of a child (even) for a moment, he has no right to deny it (later). "
شرح الحديث :
This report indicates that if a man acknowledges his paternity of a child, he has no right to deny this paternity or the child’s attribution to him later. This is because paternity is one of the rights that is established by acknowledgment, and a subsequent denial or negation is not acceptable.