The covenant with Noah after the Flood (Gn 9, 8-17)
Then God said to Noah and to his sons with him, "Behold, I establish my covenant with you and your descendants after you, and with every living creature that is with you, the birds, the cattle, and every beast of the earth with you, as many as came out of the ark. I establish my covenant with you, that never again shall all flesh be cut off by the waters of a flood, and never again shall there be a flood to destroy the earth." And God said, "This is the sign of the covenant which I make between me and you and every living creature that is with you, for all future generations: I set my bow in the cloud, and it shall be a sign of the covenant between me and the earth.
The covenant with Abraham (Genesis 15, 17-18 et 17, 1-22)
When the sun had gone down and it was dark, behold, a smoking fire pot and a flaming torch passed between these pieces. On that day the Lord made a covenant with Abram, saying, "To your descendants I give this land […] The Lord appeared to Abram, and said to him, "I am God Almighty; walk before me, and be blameless. And I will make my covenant between me and you, and will multiply you exceedingly." Then Abram fell on his face; and God said to him, "Behold, my covenant is with you, and you shall be the father of a multitude of nations [...]
The new covenant is not written anymore on tables of stone but in the hearts (Hebrews 8, 6-13)
But as it is, Christ has obtained a ministry which is as much more excellent than the old as the covenant he mediates is better, since it is enacted on better promises. For if that first covenant had been faultless, there would have been no occasion for a second. For he finds fault with them when he says: "The days will come, says the Lord, when I will establish a new covenant with the house of Israel and with the house of Judah; [...] I will put my laws into their minds, and write them on their hearts [...]
The covenant is sealed by the unique and perfect sacrifice of God's Son (Jesus) on the cross.
He is at a time the victim and the High Priest of the new covenant (Hebrews 9, 1-15)
Now even the first covenant had regulations for worship and an earthly sanctuary […]but deal only with food and drink and various ablutions, regulations for the body imposed until the time of reformation. But when Christ appeared as a high priest of the good things that have come, then through the greater and more perfect tent (not made with hands, that is, not of this creation) he entered once for all into the Holy Place, taking not the blood of goats and calves but his own blood, thus securing an eternal redemption. […]Therefore he is the mediator of a new covenant [...]