Jamieson, Fausset and Brown on Leviticus 25:39-46

39-46. if thy brother ... be waxen poor, and be sold unto thee, thou shalt not compel him to serve as a bond-servant--An Israelite might be compelled, through misfortune, not only to mortgage his inheritance, but himself. In the event of his being reduced to this distress, he was to be treated not as a slave, but a hired servant whose engagement was temporary, and who might, through the friendly aid of a relative, be redeemed at any time before the Jubilee. The ransom money was determined on a most equitable principle. Taking account of the number of years from the proposal to redeem and the Jubilee, of the current wages of labor for that time, and multiplying the remaining years by that sum, the amount was to be paid to the master for his redemption. But if no such friendly interposition was made for a Hebrew slave, he continued in servitude till the year of Jubilee, when, as a matter of course, he regained his liberty, as well as his inheritance. Viewed in the various aspects in which it is presented in this chapter, the Jubilee was an admirable institution, and subservient in an eminent degree to uphold the interests of religion, social order, and freedom among the Israelites.