The Messiah would reveal that the Hebrew Scriptures were written of Him.
OT Prophecy NT Fulfillment
Psalm 40:6–8b
[6] Sacrifice and offering thou didst not desire; mine ears hast thou opened: burnt offering and sin offering hast thou not required.
[7] Then said I, Lo, I come: in the volume of the book it is written of me,
[8] I delight to do thy will, O my God: yea, thy law is within my heart.
Luke 24:44
"And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me."

John 5:39–40
[39] Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.
[40] And ye will not come to me, that ye might have life.
Tanakh – Ketuvim – Psalms 40:7–9b
[7] Sacrifice and meal-offering Thou hast no delight in; mine ears hast Thou opened; burnt-offering and sin-offering hast Thou not required.
[8] Then said I: 'Lo, I am come with the roll of a book which is prescribed for me;
[9] I delight to do Thy will, O my G-d; yea, Thy law is in my inmost parts.
Hebrew OT – Psalms 40:7–9b
[40:7] זֶבַח וּמִנְחָה לֹא חָפַצְתָּ
אָזְנַי כָּרִיתָ
עֹלָה וַחֲטָאָה לֹא שָׁאַלְתָּ
[40:8] אָז אָמַרְתִּי הִנֵּה־בָאתִי
בִּמְגִלַּת־סֵפֶר כָּתוּב עָלָי
[40:9] לַעֲשׂוֹת רְצוֹנְךָ אֱלֹהַי חָפָצְתִּי
וְתוֹרָתְךָ בְּתוֹךְ מֵעָי