Sahih al-Bukhari 2738
صحيح البخاري#2738SahihNarrated `Abdullah bin `Umar:Allah's Messenger (ﷺ) said, "It is not permissible for any Muslim who has something to will to stay for two nights without having his last will and testament written and kept ready with him
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 55:1