The Messiah's kingdom would be eternal.
OT Prophecy NT Fulfillment
1 Chronicles 17:11–12b
[11] And it shall come to pass, when thy days be expired that thou must go to be with thy fathers, that I will raise up thy seed after thee, which shall be of thy sons; and I will establish his kingdom.
[12] He shall build me an house, and I will stablish his throne for ever.
Luke 1:31–33
[31] And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name Jesus.
[32] He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David.
[33] And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end.
Tanakh – Ketuvim – 1 Chronicles 17:11–12b
[11] And it shall come to pass, when thy days are fulfilled that thou must go to be with thy fathers, that I will set up thy seed after thee, who shall be of thy sons; and I will establish his kingdom.
[12] He shall build Me a house, and I will establish his throne for ever.
Hebrew OT – 1 Chronicles 17:11–12b
[17:11–12] כִּי יִמָּלְאוּ יָמֶיךָ לָלֶכֶת עִם־אֲבֹתֶיךָ
וַהֲקִימוֹתִי אֶת־זַרְעֲךָ אַחֲרֶיךָ אֲשֶׁר יִהְיֶה מִבָּנֶיךָ
וַהֲכִינוֹתִי אֶת־מַלְכוּתוֹ
הוּא יִבְנֶה־לִּי בַּיִת
וְכִנּוֹתִי אֶת־כִּסְאוֹ עַד־עוֹלָם