(1) باب مَا جَاءَ فِيمَا يُؤْمَرُ بِهِ مِنَ الْوَصِيَّةِ
Narrated 'Abdullah bin 'Umar:
The Messenger of Allah (ﷺ) as saying: It is the duty of a Muslim man who has something which is to be given as bequest not to have it for two nights without having his will written regarding it.
Reference: Sunan Abi Dawud 2862
In-book reference: Book 18, Hadith 1
English translation: Book 17, Hadith 2856