God’s covenant, is his contract with man, concerning the obtaining of life eternal, upon a certain condition.
This covenant consists of two parts: God’s promise to man, Man’s promise to God.
God’s promise to man, is that, whereby he binds himself to man to be his God, if he perform the condition.
Man’s promise to God, is that, whereby he vows his allegiance unto his Lord, and to perform the condition between them.
Again, there are two kinds of this covenant. The covenant of works, and the covenant of grace. Jer. 31:31, 32, 33.
“Behold the days come, says the Lord, that I will make a new covenant with the house of Israel, and with the house of Judah, not according to the covenant, I made with their fathers, when I took them by the hand to bring them out of the land of Egypt; the which my covenant they brake, although I was an husband to them, saith the Lord. But this shall be the covenant, that I will make with the house of Israel: after those days, says the Lord, I will put my law in their inward parts, and write it in their hearts, and will be their God, and they shall be my people.”
The covenant of works, is Gods covenant, made with condition of perfect obedience, and is expressed in the moral law.
The Moral Law, is that part of God’s word, which commands perfect obedience unto man, as well in his nature, as in his actions, and forbids the contrary. Romans 10. 5. “Moses thus describes the righteousness which is of the law, that the man which doth these things, shall live thereby.” 1. Timothy 1. 5. “The end of the commandment, is love out of a pure heart, and of a good conscience, and faith unfeigned.” Luke 16. 27. “You shalt love the Lord your God, with all your heart, with all your soul, and with all your strength.” Rom. 7. 14. “We know that the law is spiritual.”
The Law has two parts. The Edict, commanding obedience, and the condition binding to obedience. The condition is eternal life to such as fulfill the law, but to transgressors, everlasting death.
The Decalogue, or ten commandments, is an abridgement of the whole law, and the covenant of works. Exod. 34:27.
And the Lord said unto Moses, Write these words, for after the tenor of these words, I have made a covenant with thee, and with Israel. And be was there with the Lord forty days and forty nights, and did neither eat bread, nor drink water, and he wrote in the tables the words of the covenant, even the ten commandments. 1. King. 8. 9. Nothing was in the Ark, save the two tables of stone, which Moses had put there at Horeb, where the Lord made a covenant with the children of Israel, when he brought them out of the land of Egypt.
Mat. 22:40. “On these two commandments hangs the whole law and the prophets.”
—William Perkins (1558-1602) , Golden Chaine (Cambridge, 1616), 32. [spelling and punctuation updated
John Colquhoun’s Treatise on the Covenant of Works is another example of a Reformed theologian using Sinai as evidence of the pre-fall covenant of works:
http://theworldsruined.blogspot.com/2015/03/adamic-covenant-of-works-republished-at.html