Musannaf Ibn Abi Shayba 25:8

Ali ibn Mushir narrated to us, from Dawud, from al-Sha'bi, from Shurayh, who said: If a man asks his heirs for permission regarding a bequest, and he bequeaths more than a third, and they approve it for him, then when they have dusted their hands from his grave, they are at the beginning of their affair: if they wish, they may authorize it, and if they wish, they may not authorize it.