al-Fadl bin Dakayn, Abu Na'eem الفضل بن دكين أبو نعيم الملائي · The Book of Wills

"It is not right for a Muslim who has anything concerning which a will should be made, to abide for more than three nights without having a written will with him."

"The Messenger of Allah did not leave behind a Dinar or a Dirham, or a sheep or a camel, and he did not leave any will."