Jeremiah 34:7-11

while the king of Babylon’s army was attacking Jerusalem and all of Judah’s remaining cities — that is, Lachish and Azekah,  for they were the only ones left of Judah’s fortified cities. This is the word that came to Jeremiah from the LORD after King Zedekiah made a covenant with all the people who were in Jerusalem to proclaim freedom  to them. As a result, each was to let his male and female Hebrew slaves go free, and no one was to enslave his fellow Judean.  All the officials and people who entered into covenant to let their male and female slaves go free — in order not to enslave them any longer — obeyed and let them go free. Afterward, however, they changed their minds and took back their male and female slaves they had let go free and forced them to become slaves again.