What is the ruling on the action of a girl's father who believes that proposing to his daughter and seeking her hand in marriage is not considered a valid Sharia engagement unless the dowry (shabka) and gold are presented, and he permits his daughter to receive other suitors until the gold is brought?

An engagement is a suitor's request for marriage; it is not a legally binding contract for either party, and either can withdraw from it without embarrassment. Giving a gift during the engagement is not a requirement, but there is no harm in doing so. It is not permissible for a man to propose to an engaged woman who has already agreed [to the first suitor] unless the first suitor or her guardian withdraws, or she herself withdraws.