"It is not befitting for a Muslim to abide for three nights without having his will with him." 'Abdullah bin 'Umar said: "Since I heard this from the Messenger of Allah, I have always had my will with me."
Sunan an-Nasa'i Book 30, Hadith 8
← Previous Hadith (The same) was narrated from Ibn 'Awn, from Nafi', from Ibn 'Umar.

Sunan an-Nasa'i Book 30, Hadith 7 Next Hadith → "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."

Sunan an-Nasa'i Book 30, Hadith 9