if you want to divorce a woman so that you can marry another do not take back the dowry which you had paid even if what you paid was a large amount of gold. to do this is a slanderous act and a manifest sin.
وإن أردتم استبدال زوج مكان زوج وآتيتم إحداهن قنطارا فلا تأخذوا منه شيئا أتأخذونه بهتانا وإثما مبينا