Jeremiah 34:9

7When the king of Babylon’s army fought against Jerusalem, and against all the cities of Judah that were left, against Lachish, and against Azekah: for these defenced cities remained of the cities of Judah.

8This is the word that came unto Jeremiah from the LORD, 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.

11But afterward they turned, and caused the servants and the handmaids, whom they had let go free, to return, and brought them into subjection for servants and for handmaids.