The Ruling on a Son Marrying the Daughter of His Father’s Wife

Question:
In truth, the questions from the listener, Mu'asir Salim Jar al-Nabi al-Maliki, are good, but I do not know how this question came to his mind. He says: A man had a wife who bore him a daughter. He had a dispute with her and divorced her, and the daughter remained with her. He then married a second wife who is still with him, and she bore him a son. The son grew up, and his father wanted to marry him off. Is it permissible for this son to take the daughter whom his father’s first wife bore, the one who was before his mother?

Answer:
Marry his sister?! This is abominable! No, she is his sister, whether she is from her mother or from her father. She is his sister, and he does not marry her, whether she is his sister from his father, or his sister from his mother, or his sister from both his mother and his father. This is a strange question.
The point is: it is not permissible for him. However, if the daughter is from another man, being his daughter from a previous wife, then there is no harm. It is not a problem for him to marry his son to another wife, nor is it a problem for his son to marry the daughter of his wife from another husband. But the daughter of his wife from him is the sister of his son from the other wife, and she is not lawful for him because she is his sister.

The presenter: Thank you, may Allah reward you.