The Messiah would be eternal.
OT Prophecy NT Fulfillment
Psalm 102:25–27
[25] Of old hast thou laid the foundation of the earth: and the heavens are the work of thy hands.
[26] They shall perish, but thou shalt endure: yea, all of them shall wax old like a garment; as a vesture shalt thou change them, and they shall be changed:
[27] But thou art the same, and thy years shall have no end.
Revelation 1:8
"I am Alpha and Omega, the beginning and the ending, saith the Lord, which is, and which was, and which is to come, the Almighty."

Hebrews 1:10–12
[10] And, Thou, Lord, in the beginning hast laid the foundation of the earth; and the heavens are the works of thine hands:
[11] They shall perish; but thou remainest; and they all shall wax old as doth a garment;
[12] And as a vesture shalt thou fold them up, and they shall be changed: but thou art the same, and thy years shall not fail.
Tanakh – Ketuvim – Psalms 102:26–28
[26] Of old Thou didst lay the foundation of the earth; and the heavens are the work of Thy hands.
[27] They shall perish, but Thou shalt endure; yea, all of them shall wax old like a garment; as a vesture shalt Thou change them, and they shall pass away;
[28] But Thou art the selfsame, and Thy years shall have no end.
Hebrew OT – Psalms 102:26–28
[102:26] לְפָנִים הָאָרֶץ יָסַדְתָּ
וּמַעֲשֵׂה יָדֶיךָ שָׁמָיִם
[102:27] הֵמָּה יֹאבֵדוּ וְאַתָּה תַעֲמֹד
וְכֻלָּם כַּבֶּגֶד יִבְלוּ
כַלְּבוּשׁ תַּחֲלִיפֵם וְיַחֲלֹפוּ
[102:28] וְאַתָּה הוּא וּשְׁנוֹתֶיךָ לֹא יִתָּמוּ