(1) باب الْوَصَايَا
Narrated `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."
Reference: Sahih al-Bukhari 2738
In-book reference: Book 55, Hadith 1
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 51, Hadith 1