God gave to Adam a law of universal obedience written in his heart, and a particular precept of not eating the fruit of the tree of knowledge of good and evil; by which he bound him and all his posterity to personal, entire, exact, and perpetual obedience; promised life upon the fulfilling, and threatened death upon the breach of it, and endued him with power and ability to keep it.
The same law that was first written in the heart of man continued to be a perfect rule of righteousness after the fall, and was delivered by God upon Mount Sinai, in ten commandments, and written in two tables, the four first containing our duty towards God, and the other six, our duty to man.
Besides this law, commonly called moral, God was pleased to give to the people of Israel ceremonial laws, containing several typical ordinances, partly of worship, prefiguring Christ, his graces, actions, sufferings, and benefits; and partly holding forth divers instructions of moral duties, all which ceremonial laws being appointed only to the time of reformation, are, by Jesus Christ the true Messiah and only law-giver, who was furnished with power from the Father for that end abrogated and taken away.
To them also he gave sundry judicial laws, which expired together with the state of that people, not obliging any now by virtue of that institution; their general equity only being of moral use.
The moral law doth for ever bind all, as well justified persons as others, to the obedience thereof, and that not only in regard of the matter contained in it, but also in respect of the authority of God the Creator, who gave it; neither doth Christ in the Gospel any way dissolve, but much strengthen this obligation.
Although true believers be not under the law as a covenant of works, to be thereby justified or condemned, yet it is of great use to them as well as to others, in that as a rule of life, informing them of the will of God and their duty, it directs and binds them to walk accordingly; discovering also the sinful pollutions of their natures, hearts, and lives, so as examining themselves thereby, they may come to further conviction of, humiliation for, and hatred against, sin; together with a clearer sight of the need they have of Christ and the perfection of his obedience; it is likewise of use to the regenerate to restrain their corruptions, in that it forbids sin; and the threatenings of it serve to shew what even their sins deserve, and what afflictions in this life they may expect for them, although freed from the curse and unallayed rigour thereof. The promises of it likewise shew them God's approbation of obedience, and what blessings they may expect upon the performance thereof, though not as due to them by the law as a covenant of works; so as man's doing good and refraining from evil, because the law encourageth to the one and deterreth from the other, is no evidence of his being under the law and not under grace.
Neither are the aforementioned uses of the law contrary to the grace of the Gospel, but do sweetly comply with it, the Spirit of Christ subduing and enabling the will of man to do that freely and cheerfully which the will of God, revealed in the law, requireth to be done.