Is a sister's encouragement to her brother, who has been married for ten years and has only one child, to marry again with the intention of increasing his offspring, considered an injustice to his first wife?

Polygyny is permissible for those who can be just to their wives and fulfill their rights. It does not entail injustice to the first wife, especially if its purpose is to increase offspring, as it is better than divorcing a barren wife. Women's anger regarding polygyny is natural due to jealousy, but it does not signify injustice, because polygyny is a wise divine legislation.