I have reproduced this from the Commentary on Leviticus written by Dr. Daniel Steele in Whedon's Commentary on the Old Testament. This was originally published in 1891.
1.) The verdict of Jehovah against chattelism, and in favor of freedom as the natural inheritance of all men, is found in the sentence of capital punishment inflicted on him who steals and sells a man, or retains him in his hand. Exodus 21:16. This statute lays the axe at the very root of chattel slavery by destroying its very germ, “the wild and guilty phantasy of property in man.” For both stealing and selling assume the fact of a property value. It is to be observed that this law is universal. Stealing a man is a crime. Exodus 21:7, is not a limitation of this universal prohibition to persons of Hebrew blood. The toleration and regulation of the system of servitude in Mosaism are by no means an endorsement of its abstract rightfulness, but rather a concession to the depravity of the times. “Servitude existed before Moses. It was no part of the mission of the Hebrew code to create it. Let it be forever admitted that the laws given of God through Moses cannot be held responsible for its existence. They found it existing, and proceeded, therefore, to modifyit; to soften its more rigid features; to extract its carnivorous teeth; to ordain that the slave had rights which the master and the nation were bound to respect — in short, to tone down the severities of the system from unendurable slavery to very tolerable servitude.” — Cowles.