2 Chronicles 31:16

Beside their genealogy of males, from three years old and
upwards
Their office was not only to give to the priests, but to those of their males in their genealogy, who were three years old and upwards; for under that age, according to Kimchi, they were not fit to come into the temple; nor have they knowledge to keep what is put into their hands; nor fit to handle offerings, lest they should defile them; but at that age they might be taught how to hold them, and be used to it; but as for females, he says, they were not admitted at any age:

even unto everyone that entereth into the house of the Lord;
of the said age, and in the genealogy and register of the priests:

his daily portion for their service in their charges, according to
their courses;
food for every day, in consideration of their service in their several wards, according to their courses in turn.