This is the great quotation from the prophet Jeremiah 31:31-34 speaking before Calvary. It is new, because Christ in New Testament times came and newly paid the price for that ancient covenant of grace.
Do not these things stir us up to greater love? Do not these things deepen our sense of indebtedness? Do they not make us want to dedicate ourselves to him all the more and trust him? It would be such a sad, sad thing if a believer were to think to himself or herself, ‘Oh it is wonderful to have a high priest, who is divine and eternal, who is so accessible, who has me on his heart all the time’, and yet not be moved to dedicate themselves more fully to him. How much I owe it to him! I do not want to be one of those believers who only appreciates and takes the benefits, but one also who lives for him. This makes us want to use our remaining years in his service.
The new covenant will be made with the house of Israel and with the house of Judah. What does that mean? The verses that follow show that the new covenant is made only with those whose hearts are changed, who have the law written on their minds and their hearts, and therefore these are true believers in Christ. They are the people who are transformed in their hearts. They are not ethnic Israelites who have refused to believe the gospel. They are spiritual Israelites who include all those Gentiles who believe and are of the seed of Abraham. So why are they called the house of Israel and the house of Judah? To show us who are Israelites indeed (John 1:47).