Is it permissible to contribute to the costs of a sister's marriage after having sworn by divorce not to pay, and does the divorce take effect by purchasing anything for her?

If anger reaches the point of losing awareness when uttering an oath [of divorce], there is no harm in helping the family with the sister's wedding expenses. According to the view of Sheikh Al-Islam Ibn Taymiyyah, one can help with an expiation for the oath. However, according to the majority of scholars, such assistance [after the oath] entails divorce. If it is the first or second divorce, reconciliation is possible, but if it is the third, the wife becomes unlawful until she marries another husband. To avoid divorce, one can apologize to the family and sister and offer her gifts unrelated to the wedding expenses. It must be noted that swearing an oath by divorce is impermissible.