Musannaf Ibn Abi Shayba 13:1934

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Mansur, from Ibrahim, regarding the foundling (al-laqit). He said: His intention is for him; if he intends to be free, then he is free, and if he intends to be a slave, then he is a slave.