What is the ruling of Islamic law regarding the lineage of a child conceived through adultery by a woman in the second month of her 'iddah, then her husband took her back three months later?

The waiting period (iddah) for a revocably divorced woman who menstruates is three menstrual cycles, based on the verse: "Divorced women shall wait concerning themselves for three menstrual periods." (Al-Baqarah 2:228). The jurists have agreed that the iddah for a menstruating woman is three quru', but they differed on whether qur' refers to menstruation or purity. The Hanafis and Hanbalis held that it refers to menstruation, while the Malikis and Shafi'is held that it refers to purity. As for a divorced pregnant woman, her iddah lasts until she delivers her baby, in accordance with the verse: "And for those who are pregnant, their term is until they deliver their burden." (At-Talaq 65:4). The iddah is not calculated by months except for a young girl who does not menstruate or a woman who has reached menopause.

A revocably divorced woman during her iddah is considered to be like a wife. If she becomes pregnant during this period, the pregnancy is attributed to the husband, and he cannot deny paternity except through li'an (oath of condemnation). If she gives birth to a child less than four years after her husband divorced her, the child is attributed to him, because a pregnancy can last for four years.

If the husband revokes the divorce before the iddah ends, the revocation is valid. However, if it is after the iddah ends, the revocation is not valid, and she becomes irrevocably separated from him by a minor separation (baynunah sughra). If he wishes her to return to him, he must enter into a new marriage contract with her consent, in the presence of her guardian or his representative, and two just witnesses.