Chabad.org — English translation + Rashi
Torah Temimah points to Toras Kohanim (Sifra), Vayikra Dibbura DeNedavah, on 2:3 (le-Aharon and his sons).
Sefaria — Sifra / Toras Kohanim, Vayikra Dibbura DeNedavah
English: “To Aharon and to his sons” — to Aharon first and afterward to his sons; to Aharon without division and to his sons by division.
Diyuk of order and manner of distribution — Aharon receives first and without lots; his sons share by division.
The Kohen Gadol receives first and without lots; ordinary kohanim share by division. The Sifra reads “to Aharon and to his sons” as establishing both priority for the High Priest and two different systems of allocation: the High Priest takes without the need for lots, while the remaining kohanim divide the remainder among themselves.