What is the legal ruling regarding my sister's marriage to our paternal cousin, who does not pray and threatens to marry a second wife, especially since the marriage took place with our father's approval but without hers, and she fears confronting her father with her refusal?

A father is not permitted to marry his daughter to someone who does not pray, based on the Prophet's (peace be upon him) saying: "If there comes to you one whose religion and character you approve, then marry [your daughter] to him." A person who abandons prayer is not one whose religion is approved. The daughter should clearly explain to her father the reason for her refusal, and her brother should gently explain to their father the reason for her refusal.

As for the suitor's indication of marrying another, this is not a reason for refusal. If he commits to prayer, the daughter should accept him, due to the Prophet's (peace be upon him) saying: "The pleasure of Allah is in the pleasure of the parents, and the displeasure of Allah is in their displeasure." If she insists on refusing, her father does not have the right to compel her.