Sunan an-Nasa'i · Hadith 3616
The Book of Wills - كتاب الوصايا
أخبرنا محمد بن سلمة، قال حدثنا ابن القاسم، عن مالك، عن نافع، عن ابن عمر، أن رسول الله صلى الله عليه وسلم قال " ما حق امرئ مسلم له شىء يوصى فيه يبيت ليلتين إلا ووصيته مكتوبة عنده ".
It was narrated from Ibn 'Umar that the Messenger of Allah said: "It is not befitting for a Muslim who has anything concerning which a will should be made, to abide for two nights without having a written will with him."
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).