Matthew Poole and continuators on Deuteronomy 15:3

3 Of a forreigner thou mayest exact it again: but that which is thine with thy brother, thine hand shall release.

Or stranger, yea though a proselyte, for 1. They are oft called by this name, as Gen. 17. 12. Ruth 2. 10. 2. Though proselytes were admitted to the Church-priviledges of the Israelites, yet they were not admitted to all their civil immunities or priviledges. See 1 Chron. 22. 2. and 2 Chron. 2. 17. 3. Such were not then freed from their personal debt, to wit, of their service, Levit. 25. 44. Deut. 15. 12. Ier. 34. 14. therefore not from their real debt.

To wit, by right though lent to him.