1) God's covenant with Abraham the NT describes by the term "Promise".
2) God's covenant with Israel through Moses the NT describes by the term "Law".
3) The New Covenant the NT describes by the term "Faith"
It is clear that Paul views the Law as fundamentally different from both Promise and Faith:
"For if the inheritance depends on the law, then it no longer depends on the promise; but God in his grace gave it to Abraham through a promise." Gal 3:18
"The law is not based on faith; on the contrary, it says, "The person who does these things will live by them." Gal 3:12
Paul repeatedly speaks of the Mosaic Covenant in terms of "works", in contrast with "faith."
"For all who rely on works of the law are under a curse; for it is written, “Cursed be everyone who does not abide by all things written in the Book of the Law, and do them.” Now it is evident that no one is justified before God by the law, for “The righteous shall live by faith.”12 But the law is not of faith, rather “The one who does them shall live by them..” Gal 3:10-12
"When Israel sinned, no prophet ever interceded for the nation on the basis of Law, but solely on the basis of grace, imploring God for mercy and appealing to the covenant God had made with Abraham. Isaac, and Jacob." (See Ex 32:12-14; Deut 9:24-27; 2 Kings 13:22-23)
Charles Leiter