The commands here are repeated from Exodus 21:2-6, with amplifications relative to the maidservant Deuteronomy 15:12 and to the making (Deuteronomy 15:13 ff) liberal provision for launching the freedman on an independent course of life. The release of the servant is connected with the sabbatical principle though not with the sabbatical year. It is noteworthy also that the prospect of a gift of this sort, the amount of which was left to the master‘s discretion, would be likely to encourage diligence and faithfulness during the years of servitude.
Deuteronomy 15:18
He hath been worth a double hired servant to thee, in serving thee six years - “i. e.” such a servant has earned twice as much as a common hired laborer would have done in the same time.