The great 17th century Reformed theologian, Herman Witsius, believed in the doctrine that now goes by the infelicitous name “republication.” He taught that there was a repetition of the Adamic covenant of works in the Mosaic economy, not intended to be the means of the salvation of the Israelites, but to show them their sin and lead them to Christ. The “do this and live” principle (Lev 18:5) was “subservient” to the covenant of grace.
And hence we must judge what Paul understands by the law of works, what by the works of the law, and what by faith. The law of works is that which demands works to be done by man himself, as the condition of life, or the cause of claiming the reward: the tenor of which is this, The man who doeth these things shall live in them, Rom 10:5. Such a law was given to Adam of old, who, if he had persevered in his integrity, would have obtained a right to eternal life by his works of righteousness.
The same doctrine Moses repeated in his ministry. For he also inculcated the same precepts upon which the covenant of works had been built: he both repeated the same solemn saying, He who doeth these things shall live in them, Lev 18:5, and also added another, Cursed be he who shall not perform the words of this law in doing them, Deut 27:26. That this is the curse of the law, as it stands opposed to the covenant of grace, Paul teacheth, Gal 3:10, which, however, is not so to be understood, as if God had intended, by the ministry of Moses, to make a new covenant of works with Israel, with a view to obtain righteousness and salvation by such a covenant. But that repetition of the covenant of works was designed to convince the Israelites of their sin and misery, to drive them out of themselves, to teach them the necessity of a satisfaction, and to compel them to cleave to Christ: and thus it was subservient to the covenant of grace, Rom 10:4.
Herman Witsius, Conciliatory or Irenical Animadversions on the Controversies Agitated in Britain Under the Unhappy Names of Antinomians and Neonomians (trans. Thomas Bell; Glasgow: W. Lang, 1807; originally published in Latin in 1696), 86-87.