Abdur Rahman ibn Hurmuz al-Araj said: Al-Abbas ibn Abdullah ibn al-Abbas married his daughter to Abdur Rahman ibn al-Hakam, and Abdur Rahman married his daughter to him. And they made this (exchange) their dower. Muawiyah wrote to Marwan commanding him to separate them. He wrote in his letter: This is the shighar which the Messenger of Allah ﷺ has forbidden.