Heb 8:10-12
"For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my laws into their minds, and write them on their hearts, and I will be their God, and they shall be my people. And they shall not teach, each one his neighbor and each one his brother, saying, ‘Know the Lord,’ for they shall all know me, from the least of them to the greatest."
The quotation of Jer 31:31-34 — the only time the OT explicitly uses 'new covenant.' The four characteristics of the New Covenant: (1) internalized law — on the heart, not on stone; (2) personal relationship — 'I will be their God'; (3) direct knowledge of God — without necessary priestly mediation; (4) complete forgiveness — 'I will remember their sins no more.'