The Messenger of Allah ﷺ said, "It is not fitting for a Muslim who has something to bequeath to let two nights pass without having his will written and kept with him."
حدثني مالك عن نافع
أن رسول الله ﷺ قال ما حق امرئ مسلم له شيء يوصى فيه يبيت ليلتين إلا ووصيته عنده مكتوبة