King David divided the Levite priests into 24 family groups, called “divisions” or “courses,” which took turns ministering at the altar in Jerusalem for a week at a time, twice-a-year.
This rotating schedule, called sacerdotal rota system, is recorded in I Chronicles 24:
“The sons of Aaron … served as the priests … David separated them into divisions for their appointed order of ministering …
The first lot fell to Jehoiarib,
the second to Jedaiah,
the third to Harim,
the fourth to Seorim,
the fifth to Malkijah,
the sixth to Mijamin,
the seventh to Hakkoz,
the eighth to Abijah…” (The list continues through the twenty-four family divisions.)
The family course of Abijah served in the annual cycle on the 8th week and the 32nd week.
Solomon initiated the courses when he dedicated the First Temple in mid-10th century BC. 2 Chronicles 8:12-14 records:
“Solomon … in keeping with the ordinance of his father David, he appointed the divisions of the priests for their duties.”