Chabad.org — English translation + Rashi
Torah Temimah points to Toras Kohanim (Sifra), Vayikra Dibbura DeNedavah, on 2:15 (minchah hi — include miluim day-eight).
Sefaria — Sifra / Toras Kohanim, Vayikra Dibbura DeNedavah
English: “It is a minchah” — to include the eighth-day [miluim] minchah for frankincense.
Ribbuy of miluim minchah for levonah — the eighth-day consecration minchah also receives frankincense.
The minchah of the eighth day of the consecration also receives levonah. The Sifra reads “it is a minchah” as including the special offering of the miluim among those that take frankincense.