Chronicles II 31:17

17 This the distribution of the priests according to the houses of their families; and the Levites in their daily courses from twenty years old and upward in order,

Chronicles II 31:17 Meaning and Commentary

2 Chronicles 31:17

Both to the genealogy of the priests by the house of their
fathers
As to the priests registered according to their families from the age before observed, a portion was given: so to the Levites,

from twenty years old and upward, in their charges, by their courses;
for though originally they were not admitted into the tabernacle till twenty five years of age, nor to officiate till thirty, but in David's time they were allowed at twenty years of age and upwards, ( 1 Chronicles 23:24 ) .

Chronicles II 31:17 In-Context

15 by the hand of Odom, and Benjamin, and Jesus, and Semei, and Amarias, and Sechonias, by the hand of the priests faithfully, to give to their brethren according to the courses, as well to great as small;
16 besides the increase of males from three years old and upward, to every one entering into the house of the Lord, according to a daily rate, for service in the daily courses of their order.
17 This the distribution of the priests according to the houses of their families; and the Levites in their daily courses from twenty years old and upward in order,
18 to assign stations for all the increase of their sons and their daughters, for the whole number: for they faithfully sanctified the holy place.
19 As for the sons of Aaron that executed the priests' office, —even those from their cities the men in each several city who were named expressly, — to give a portion to every male among the priests, and to every one reckoned among the Levites.

The Brenton translation of the Septuagint is in the public domain.