knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law; for by the works of the law shall no flesh be justified.

Is the law then against the promises of God? No, in no wise, for if there had been a law given which could have given life, verily righteousness should have been by the law.

Behold, I, Paul, say unto you that if ye become circumcised, Christ shall profit you nothing.

For they, being ignorant of God's righteousness and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God.

And if by grace, then is it not by works; otherwise, the grace is no longer grace. But if it is of works, then it is no longer grace; otherwise, the work is no longer work.

If therefore perfection were by the Levitical priesthood (for under it the people received the law), what further need was there that another priest should rise after the order of Melchisedec and not be called after the order of Aaron?

Christ

But I said, I have laboured in vain; I have spent my strength for nothing, and in vain; yet surely my judgment is before the LORD and my recompense with my God.

How do ye say, We are wise, and the law of the LORD is with us? Behold, certainly in vain did he make the pen; the scribes were in vain.

by which also ye are being saved if ye retain the word that I preached unto you, unless ye have believed in vain.

General references

And ye shall take no ransom for him that is fled to the city of his refuge, that he should come again to dwell in the land, until the death of the priest.

For if I build again the things which I destroyed, I make myself a rebel.