Jeremiah 34:8-10

8This is the word that came unto Jeremiah from Yhwh, after that the king Zedekiah had made a covenant with all the people which were at Jerusalem, to proclaim liberty unto them; 9That every man should let his manservant, and every man his maidservant, being an Hebrew or an Hebrewess, go free; that none should serve himself of them, to wit, of a Jew his brother. 10Now when all the princes, and all the people, which had entered into the covenant, heard that every one should let his manservant, and every one his maidservant, go free, that none should serve themselves of them any more, then they obeyed, and let them go.