That Christ was to be born of the seed of David, according to the flesh
In the second of Kings: “And the word of the Lord came to Nathan, saying, Go and tell my servant David, Thus says the Lord, You shall not build me an house to dwell in; but it shall come to pass, when your days shall be fulfilled, and you shall sleep with your fathers, I will raise up your seed after you who shall come from your loins, and I will establish His kingdom. He shall build me a house in my name, and I will set up His throne for ever; and I will be to; Him a Father, and He shall be to me a Son; and His house shall obtain confidence, and His kingdom for ever in my sight.” Also in Isaiah: “And a rod shall go forth of the root of Jesse, and a flower shall go up from his root; and the Spirit of the Lord shall rest upon Him, the spirit of wisdom and of understanding, the spirit of counsel and might, the spirit of knowledge and piety; and the spirit of the fear of the Lord shall fill Him.” Also in the cxxxist Psalm: “God has sworn the truth unto David himself, and He has not repudiated it; of the fruit of your belly will I set upon my throne.” Also in the Gospel according to Luke: “And the angel said unto her, Fear not, Mary. For you have found favour before God. Behold, you shall conceive, and shall bring forth a son, and shall call His name Jesus. The same shall be great, and He shall be called the Son of the Highest; and the Lord God shall give Him the throne of His father David, and He shall reign over the house of Jacob for ever, and of His kingdom there shall be no end.” Also in the Apocalypse: “And I saw in the right hand of God, who sate on the throne, a book written within, and on the back sealed with seven seals; and I saw a strong angel proclaiming with a loud voice, Who is worthy to receive the book, and to open its seals? Nor was there any one either in heaven or upon the earth, or under the earth, who was able to open the book, nor even to look into it. And I wept much because nobody was found worthy to open the book, nor to look into it. And one of the elders said unto me, Weep not; behold, the Lion of the tribe of Judah, the Root of David, has prevailed to open the book, and to loose its seven seals.”
Source: The Treatises of Cyprian (New Advent)