וְאֶל־בְּנֵ֥י יִשְׂרָאֵ֖ל תְּדַבֵּ֣ר לֵאמֹ֑ר שֶׁ֠מֶן מִשְׁחַת־קֹ֨דֶשׁ יִהְיֶ֥ה זֶ֛ה לִ֖י לְדֹרֹתֵיכֶֽם׃
And thou shalt speak unto the children of Israel, saying: This shall be a holy anointing oil unto Me throughout your generations.
Rashi on Exodus
לדרתיכם THROUGHOUT YOUR GENERATIONS — From here our Rabbis derived that it (the oil of anointment) was miraculously preserved in its entirety for the time to come (for the Messianic days) (Horayot 11b).
Sforno on Exodus
יהיה זה לי לדורותיכם, this oil of holy anointing for Me will last throughout your generations.