Musannaf Ibn Abi Shayba 25:16

Waki’ narrated to us, he said: Sufyan narrated to us, from Mansur, from Ibrahim, from Dawud ibn Abi Hind, from ‘Amir, and from Khalid, from Ibn Sirin, from Shurayh, who said: If a man makes a bequest during his illness of more than one-third to a non-heir or to an heir, and the heirs permit it, then he dies, they have the right to retract [their permission].