Musnad Ahmad 769:35

'Abd al-Rahman ibn Mahdi narrated to us, Malik—meaning Ibn Mighwal—narrated to me, from Talhah ibn Musarrif, who said: I asked 'Abdullah ibn Abi Awfa: "Did the Messenger of Allah, may Allah bless him and grant him peace, make a will?" He said: "No." I said: "Then why was the will prescribed for the Muslims, or why were they commanded to make a will?" He said: "He enjoined the Book of Allah, the Mighty and Majestic."