Exodus 21:1-36 (New King James Version of the Bible)
¹  "Now these are the judgments which you shall set before them:
²  If you buy a Hebrew servant, he shall serve six years; and in the seventh he shall go out free and pay nothing.

            Cf. Jacob, Rachel and Leah.  Genesis 29:30 
³  If he comes in by himself, he shall go out by himself; if he comes in married, then his wife shall go out with him.
⁴  If his master has given him a wife, and she has borne him sons or daughters, the wife and her children shall be her master's, and he shall go out by himself.
⁵  But if the servant plainly says, 'I love my master, my wife, and my children; I will not go out free,'
⁶  then his master shall bring him to the judges. He shall also bring him to the door, or to the doorpost, and his master shall pierce his ear with an awl; and he shall serve him forever.

Note:  This is the practice of a bondslave.  Paul referred to himself as a bondslave of Christ. (Romans 1:1)   How strange it is that the greatest freedom is gained by willingly becoming a slave.  It is all a matter of whose slave.

⁷  "And if a man sells his daughter to be a female slave, she shall not go out as the male slaves do.
⁸  If she does not please her master, who has betrothed her to himself, then he shall let her be redeemed. He shall have no right to sell her to a foreign people, since he has dealt deceitfully with her.
⁹  And if he has betrothed her to his son, he shall deal with her according to the custom of daughters.

Note:  Here betrothal and marriage is seen as a form of slavery. 

¹⁰  If he takes another wife, he shall not diminish her food, her clothing, and her marriage rights.

Note:  These are uncomfortable applications of the Law, because there is nothing that I read in them that condemns slavery.  Take a look at verse 4, in which the slave is allowed freedom but his wife and children must stay.  What loving husband and father would accept such terms?  But some choose to stay with family, and with their master, and become bondslaves-slaves for life.  (See note about Romans 1:1 above)

Note:  The Law, I suspect, improves the lot of the slave because slaves seem to have no rights in other situations.  I'd like to think this is an example of the Bible reporting the existence of slavery as culturally accepted as opposed to God approving the institution of slavery.  Numerous passages in the prophets and other places speak of God's will involving "breaking the yoke" and "letting the captive go free".  Even part of Jesus' mission statement (Luke 4:18-19) is "to set at liberty those who are oppressed".  Or look, for example, at Isaiah 58:6 "Is this not the fast that I have chosen:  to loose the bonds of wickedness, to undo the heavy burdens, to let the oppressed go free, and that you break every yoke?"  Then there is the Year of Jubilee, the like of which is not found in our culture:  Leviticus 25:10 "And you shall consecrate the fiftieth year, and proclaim liberty throughout all the land to all its inhabitants.  It shall be a Jubilee for you; and each of you shall return to his possession, and each of you shall return to his family."

The subject of slavery is, unfortunately, very relevant today, for human trafficking remains a serious problem.  I would also add economic slavery, in which businesses seek to keep people in debt all of their lives.  Such slaves have no time limit, nor any rights whatsoever.  We should pray for vision to see the need and wisdom to know what to do about it.  Look for specific situations where you live.  You might be surprised to find how people are suffering near where you live.