Leviticus 9:1

ויהי ביום השמיני AND IT CAME TO PASS ON THE EIGHTH DAY of the installation of the priests into their sacred office (cf. Sifra); this was the New Moon of Nisan on which the Tabernacle was finally erected (cf. Rashi on Exodus 40:29) and it (that day) received ten crowns (it was distinguished in ten different ways) which are enumerated in Seder Olam 7 (Sifra, Shemini, Mechilta d'Miluim 2 1; Shabbat 87b). ולזקני ישראל AND TO THE ELDERS OF ISRAEL, to inform them that it was by the express command of God that Aaron was entering the Sanctuary and ministering in the high-priesthood, so that they might not say: “He is entering on his own authority, unbidden.”

וַֽיְהִי֙ בַּיּ֣וֹם הַשְּׁמִינִ֔י קָרָ֣א מֹשֶׁ֔ה לְאַהֲרֹ֖ן וּלְבָנָ֑יו וּלְזִקְנֵ֖י יִשְׂרָאֵֽל׃

And it came to pass on the eighth day, that Moshe called Aharon and his sons, and the elders of Yisra᾽el: