God's Unfailing Promise to King David

But that same night the word of the LORD came to Nathan, "Go and tell my servant David, 'Thus says the LORD [Covenant]... When your days are fulfilled and you lie down with your fathers, I will raise up your offspring after you, who shall come forth from your body, and I will establish his kingdom. He shall build a house for my name, and I will establish the throne of his kingdom for ever. I will be his father, and he shall be my son. When he commits iniquity, I will chasten him with the rod of men, with the stripes of the sons of men; but I will not take my steadfast love from him, as I took it from Saul, whom I put away from before you. And your house and your kingdom shall be made sure for ever before me; your throne shall be established for ever.'" In accordance with all these words, and in accordance with all this vision, Nathan spoke to David.
(2 Samuel 7:4-5,12-17)

Thou hast said, "I have made a covenant with my chosen one,
I have sworn to David my servant:

'I will establish your descendants for ever,
and build your throne for all generations.'" [Selah]
(Psalms 89:3,4)

The word of the LORD came to me: "Son of man, take a stick and write on it, 'For Judah, and the children of Israel associated with him'; then take another stick and write upon it, 'For Joseph (the stick of E'phraim) and all the house of Israel associated with him'; and join them together into one stick, that they may become one in your hand. And when your people say to you, 'Will you not show us what you mean by these?' say to them, Thus says the Lord GOD: Behold, I am about to take the stick of Joseph (which is in the hand of E'phraim) and the tribes of Israel associated with him; and I will join with it the stick of Judah, and make them one stick, that they may be one in my hand. When the sticks on which you write are in your hand before their eyes, then say to them, Thus says the Lord GOD: Behold, I will take the people of Israel from the nations among which they have gone, and will gather them from all sides, and bring them to their own land; and I will make them one nation in the land, upon the mountains of Israel; and one king shall be king over them all; and they shall be no longer two nations, and no longer divided into two kingdoms. They shall not defile themselves any more with their idols and their detestable things, or with any of their transgressions; but I will save them from all the backslidings in which they have sinned, and will cleanse them; and they shall be my people, and I will be their God. "My servant David shall be king over them; and they shall all have one shepherd. They shall follow my ordinances and be careful to observe my statutes. They shall dwell in the land where your fathers dwelt that I gave to my servant Jacob; they and their children and their children's children shall dwell there for ever; and David my servant shall be their prince for ever. I will make a covenant of peace with them; it shall be an everlasting covenant with them; and I will bless them and multiply them, and will set my sanctuary in the midst of them for evermore. My dwelling place shall be with them; and I will be their God, and they shall be my people. Then the nations will know that I the LORD sanctify Israel, when my sanctuary is in the midst of them for evermore."
(Ezekiel 37:15-28)