Musannaf Ibn Abi Shayba 13:3127

Abu Bakr narrated to us, he said: Yahya ibn Adam narrated to us, he said: Abu Bakr al-Nahshali narrated to us, from Muhammad ibn Qays, from Habib ibn Abi Thabit, from Tawus, that a man asked him and said: "I have made my slave-girl free if I sell her for less than such and such [amount], and I fear that the season will end before I sell her, so he wants to sell her for less than what I said." He said: "If you do not fear the authority, or were it not that I fear the authority for you..."