It is not befitting for a Muslim who has anything concerning which a will should be made, to abide for two nights without having his will with him.[Al-Bukhari]
«ما حق امرئ مسلم له شيء يوصي فيه؛ يبيت ليلتين إلا ووصيته مكتوبة عنده». [صحيح.] - [متفق عليه.]