What is obligatory upon one who married his milk-sister without knowing it?

Question:
A man married a woman, and he knew that she was not permissible for him due to breastfeeding, because he was the nursling of her younger sister. He did not know this until after he divorced her, and she had given birth to a child for him. Is it obligatory for him to pay an expiation, or something similar?

The Shaykh: Repeat, repeat.

The presenter: He says: A man married a woman, and he knew that she was not permissible for him due to breastfeeding, because he was the nursling of her younger sister. He did not know this until after he divorced her, and she had given birth to a child for him. Is it obligatory for him to pay an expiation, or something similar?

Answer:
He owes nothing, as long as he did not know, he owes nothing. His child is valid, his child is attributed to him, and praise be to Allah; because he did not intentionally commit what is invalid. Yes.

The presenter: May Allah reward you with good.