Sunan an-Nasa'i 3619
سنن النسائي#3619SahihIt was narrated from Salim bin 'Abdullah, from his father, that the Messenger of Allah said:"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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 30:9