Musannaf Ibn Abi Shayba 13:705

Abu Bakr narrated to us, he said: Ibn Fudayl narrated to us, from Husayn, from al-Sha'bi, who said: The one emancipated via *tadbir* (a conditional manumission effective upon the master's death) is in the status of a slave, except that he is not sold and he is not gifted. If his master dies, he is emancipated.