Exodus 28:10

“Six of their names on one stone, etc.] The names of the six eldest on the stone upon the right shoulder: and the other six names of the rest on the other stone: the names of the six youngest on the stone upon the left shoulder; for these stones, as afterwards said, were put on the shoulders of the priests, according to their birth; the order of it; so that upon the first stone were engraven the names of Reuben, Simeon, Levi, Judah, Dan, and Naphtali; and on the second stone the names of Gad, Asher, Issachar, Zebulun, Joseph, and Benjamin; and so they are disposed by Jarchi, with whom Josephus agrees f819; though some Jewish writers, and particularly Maimonides f820, place them otherwise; but…”

“(Compare Exodus 39:1-31.) Moses is now commanded to commit all that pertains to the offerings made to the Lord in the sanctuary to the exclusive charge of the members of a single family, who were to hold their office from generation to generation. In the patriarchal times, the external rites of worship had generally been conducted by the head of the tribe or family, in accordance with the principle involved in the dedication of the firstborn Exodus 13:2; Numbers 3:12-13. Moses, as the divinely-appointed and acknowledged leader of the nation, had, on a special occasion, appointed those who were to offer sacrifice, and had himself sprinkled the consecrating blood of the victims on the people…”

“according to their birth: Exo 1:1-4; Gen 43:33 Exodus 28:11”