Jeremiah 34:10
Now 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.
The verse belongs to what happened during the Babylonian siege of Jerusalem, in the two years before the city fell. The princes and all the people who had entered the covenant obeyed Zedekiah's proclamation by letting every Hebrew manservant and every maidservant go free, so that none would be made to serve any longer.
The release was the act of liberty required by a covenant made with a sacrifice prepared by dividing its pieces, with the covenant parties passing between them. It was part of the king's attempt to carry out the scriptural requirements of the jubilee, for relief of those in debt or otherwise oppressed, such as had not been carried out since the time of Moses. After obeying, the people took back those they had freed, and breaking their promise polluted the Lord's name.
The surrounding account makes the Jews' later oppression and enslavement a principal part of God's indictment against them before Nebuchadnezzar destroyed them. Israel had been commanded to secure servants' freedom, but disobeyed and adopted slavery like the surrounding nations, which the prophets condemned and God judged through Nebuchadnezzar. Allowing Israelites to hold slaves was not pleasing to God and violated the moral law, being only tolerated under special civil precepts because of the people's corruption rather than set as a moral standard.
The covenant pattern helps explain God's covenant with Abraham, in which the sacrifice represents Christ who gives freedom from the bondage of sin.