Adam Clarke on Deuteronomy 15:9

Beware that there be not a thought in thy wicked heart - לבבך בליעל lebabecha beliyaal, thy belial heart, that is, thy good-for-nothing or unprofitable heart; See on Deu 13:13 (note).

And thine eye be evil - An evil eye signifies a covetous disposition. See the same form of expression used by our Lord in the same sense, Mat 6:23. If thine eye be evil - If thou be a covetous person. Evil eye is by our Lord opposed to single eye, i. e., a person of a liberal, benevolent mind. Covetousness darkens the soul; liberality and benevolence enlighten it.

And he cry unto the Lord against thee - What a consolation to the poor and the oppressed, that they have a sure friend in God, who will hear their cry and redress their grievances!