Luke 22:20 which reads: "this cup that is poured out for you is the new covenant in my blood".[6][7]
The New Covenant (Ancient Greek: διαθήκη καινή, romanized: diathḗkē kainḗ) is a biblical interpretation which was originally derived from a phrase in the Book of Jeremiah (Jeremiah 31:31–34), in the Hebrew Bible (or the Old Testament of the Christian Bible). Generally, Christians believe that the promised New Covenant—new relationship with God—was instituted at the Last Supper as part of the Eucharist[1][2] which, in the Gospel of John, includes the New Commandment.
the authors of the New Testament and Christian leaders generally, consider Jeremiah 31:31–34 to be a central Old Testament prophecy of the New Covenant.[8] Here is the key text:
Behold, the days are coming, declares the Lord, when I will make a new covenant with the house of Israel and the house of Judah, not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt, my covenant that they broke, though I was their husband, declares the Lord. For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. And no longer shall each one teach his neighbor and each his brother, saying, "Know the Lord," for they shall all know me, from the least of them to the greatest, declares the Lord. For I will forgive their iniquity, and I will remember their sin no more.