“the seventh year, the year of release.” According to the Law of Moses, every seventh year was a year of release. On the seventh year, slaves had to be released, and they could not be sent away empty-handed, they had to be given enough to start their life again (Exod. 21:2; Deut. 15:12-15), the land had to be released from its labor and not cultivated (Exod. 23:11; Lev. 25:4-7; Neh. 10:32), and any debt that was owed to a brother Israelite had to be forgiven (Deut. 15:1-3; Neh. 10:32).
The “seventh year” was fixed on the calendar. For example, if you lent money to someone, the “seventh year” was not seven years later, but when the “seventh year” came up, which might have been the very next year. Here in Deuteronomy 15:9 God warns the Israelites not to be stingy and have an “evil eye” against their fellow Israelite and to lend to the needy even if the year of release was near and the chances of being repaid were slim.
“your eye be evil.” The “evil eye” is a Semitic idiom for being greedy and stingy. God is telling people not to be stingy, but to give to their needy brother even if the year of release, the seventh year, is close and it does not look like the needy one will be able to pay you back before his debt is released. Biblically, an evil eye is greedy or stingy; while a “good eye,” or a “single eye,” is generous.
[For more on idioms involving the good eye, see commentary on Prov. 22:9. For more on the idiom of the evil eye, see commentary on Prov. 28:22.]