John Wesley on Exodus 21

The first verse is the general title of the laws contained in this and the two following chapters. Their government being purely a theocracy; that which in other states is to be settled by human prudence, was directed among them by a divine appointment. These laws are called judgments; because their magistrates were to give judgment according to them. In the doubtful cases that had hitherto occurred, Moses had particularly enquired of God, but now God gave him statutes in general, by which to determine particular cases. He begins with the laws concerning servants, commanding mercy and moderation towards them. The Israelites had lately been servants themselves, and now they were become not only their own matters, but masters of servants too; lest they should abuse their servants as they themselves had been abused, provision was made for the mild and gentle usage of servants.

If thou buy an Hebrew servant - Either sold by him or his parents through poverty, or by the judges for his crimes, yet even such a one was to continue in slavery but seven years at the most.

For ever - As long as he lives, or till the year of Jubilee.

Who hath betrothed her to himself - For a concubine, or secondary Wife. Not that Masters always took Maid - servants on these terms.

After the manner of daughters - He shall give her a portion, as to a daughter.

Direction is given what should be done, if a servant died by his master's correction. This servant must not be an Israelite, but a Gentile slave, as the Negroes to our planters; and it is supposed that he smite him with a rod, and not with any thing that was likely to give a mortal wound, yet if he died under his hand, he should be punished for his cruelty, at the discretion of the judges, upon consideration of circumstances.

Eye for eye - The execution of this law is not put into the hands of private persons, as if every man might avenge himself, which would introduce universal confusion. The tradition of the elders seems to have put this corrupt gloss upon it. But magistrates had an eye to this rule in punishing offenders, and doing right to those that are injured.