Deuteronomy 15

"It shall not seem hard to you when you send him away free from you; for he has been worth a double hired servant in serving you six years. Then the Lord your God will bless you in all that you do." v.18

Read chapter 15
This is a repeat of the law, but with an addition that masters were to send provisions with them as their earnings once they were set free after six years.  The difference in the hired servant and the slave was a great contrast.  The hired servant earned wages, were hired yearly for at most three years (Lev. 25:53).  The slave, or bondservant, did not receive wages except for food and housing and served for six years.  The difference of both time and money was double profit to the owner of the slave than the hired servant.  So when the master sets his servant free he should not grumble and give freely the abundance that the Lord has blessed him with.  Masters were not to harden their heart towards giving (v.7) to the poor of their brethren or their slaves (which were foreigners as the Israelites were not to enslave their fellow Jews, Lev.25:39-43).  The slave could've fallen in love with their master or felt secure staying there and could commit to him for life by putting an awl through his or her ear, but that was a decision of the slave not the master.  Now we don't have slaves here in the United States today, but flip it the other way and realize we're bondservants to Christ as we see Paul refer to himself so often (see Phil. 1, Titus 1).  We may not earn wages from Him in this life, but we are provided for and our treasure is in heaven.  We are the bondservants that have committed to Christ our Master not just for six years but forever!