What is the legitimate Islamic method for determining a child's lineage, and is it permissible in Islamic law to attribute the child's lineage to the husband despite doubt, and is it better to divorce or to abandon the wife while continuing to provide for her?

The child carried by the wife is legally attributed to her husband, even if she commits adultery, based on the Prophet's (peace be upon him) saying: "The child belongs to the bed, and for the adulterer is the stone." If the husband becomes certain that the child is not his, he must disown it through li'an. The wife must offer sincere repentance from adultery by abandoning it, regretting it, and resolving not to return to it. If the wife repents, he may keep her and conceal her sin.