The law and the gospel agree
From all this we may learn that there is no opposition at all between the law and the gospel, that there is no need for the law to pass away in order to establish the gospel. Indeed neither of them replaces the other, but they agree perfectly well together. Yes, the very same words, considered in different respects, are parts both of the law and of the gospel. If they are considered as commandments, they are parts of the law. If as promises, of the gospel. Thus, you shall love the Lord your God with all your heart (Deuteronomy 6:5), when considered as a commandment, is a branch of the law. When regarded as a promise, it is an essential part of the gospel, the gospel being nothing other than the commands of the law proposed by way of promises. Accordingly, poverty of spirit, purity of heart (Matthew 5:8), and whatever else is commanded in the holy law of God, are nothing other, when viewed in a gospel light, than so many great and precious promises (2 Peter 1:4).
1771 text
2. From all this we may learn, that there is no contrariety at all, between the law and the gospel; that there is no need for the law to pass away, in order to the establishing the gospel. Indeed neither of them supersedes the other, but they agree perfectly well together. Yea, the very same words, considered in different respects, are parts both of the law and of the gospel: if they are considered as commandments, they are parts of the law; if as promises, of the gospel. Thus, Thou shalt love the Lord thy God with all thy heart, when considered as a commandment, is a branch of the law: when regarded as a promise, is an essential part of the gospel: the gospel being no other than the commands of the law, proposed by way of promises. Accordingly poverty of spirit, purity of heart, and whatever else is injoined in the holy law of God, are no other, when viewed in a gospel light, than so many great and precious promises.