Sayyiduna Khawwat bin Jubayr (may Allah be pleased with him) says: A man died and made me (his executor), and among what he left were his umm walad (a slave woman who had borne him a child) and a free woman. Then some words passed between the umm walad and that woman, and the woman said to her: "O foolish one! Tomorrow you will be taken by the ear and sold in the market." I mentioned this to the Messenger of Allah (peace and blessings be upon him), and he (peace and blessings be upon him) said: "She will not be sold."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4132