Amr bin 'Ali bin Bahr al-Bahli عمرو بن علي بن بحر الباهلي · The Book of Wills

"It is not befitting for a Muslim who has anything concerning which a will should be made, to abide for two nights without having a written will with him."

"I asked Ibn Abi Awfa: 'Did the Messenger of Allah leave a will?' He said: 'No.' I said: 'How come it is prescribed for the Muslims to make wills?' He said: 'He left instructions urging the Muslims to adhere to the Book of Allah.'"

"Sa'd bin 'Ubadah Al-Ansari consulted the Messenger of Allah about an (outstanding) vow that his mother had to fulfill, but she died before doing so. The Messenger of Allah said: 'Fulfill it on her behalf.'"