Matthew Poole and continuators on Jeremiah 34:9

9 That every man should let his man-servant, and every man his maid-servant being an Hebrew, or an Hebrewess go free, that none should serve himself of them, to wit, of a Jew his brother .

This was the tenour of Gods Law mentioned in the above-named Texts, and it seemeth Zedekiah taking notice of the common violation of this Law, and the Jews ordinary oppressing those of their own nation this way, judging that this might be one of those sins for which the wrath of God was at this time kindled against them, he caused the people to make a Covenant, that they would give that liberty to their Servants of either Sex, which the Law of God required of which he made Proclamation.

Marginal references: Neh. 5.11.