You are correct, I should have said servant, not slave....However, the master does NOT have the choice as to whether the wife and children go free. The servant has the choice of leaving alone or staying a servant of the master forever, in this way he can stay with his wife and children.
YLTLev 18:4`
My judgments ye do,and My statutes ye keep, to walk in them; I am Jehovah your God;
Lev 18:5and ye have kept My statutes and
My judgments which man doth and liveth in them;I am Jehovah.
The are many judgements in Exodus that are listed in the 613 Laws of Moses.
http://www.jewfaq.org/613.htm
Exo 21:2`When thou
buyesta Hebrew servant--six years he doth serve, and in the seventh he goeth out as a freeman for nought;
Exo 21:3if by himself he cometh in, by himself he goeth out;if he is owner of a wife, then his wife hath gone out with him;
Exo 21:4if his lord give to him a wife,and she hath borne to him sons or daughters--the wife and her children
are her lord's, and
he goeth out by himself.Exo 21:5`And if the servant really say: I have loved my lord, my wife, and my sons--I do not go out free;
Exo 21:6then hath his lord brought him nigh unto God, and hath brought him nigh unto the door, or unto the side-post, and his lord hath bored his ear with an awl, and
he hath served him--to the age.
If one is bought, one is in bondage are they not? And even when they are freed, their wife and children do not belong to them, the belong to the master and they are not free to to leave with him.
Where do you see the master has a choice to release the wife and children? It may be true but I don't remember ever reading that in the scriptures, it is not here in Exodus where the judgment is spoken.
These statues and judgements, Law of Moses, that YHVH, said anyone under the Law of Moses must keep them.