Ezra 6:18
And they set the priests in their divisions, and the Levites in their courses, for the service of God, who is at Jerusalem; as it is written in the book of Moses.
Numbers 3:6
Bring the tribe of Levi near, and present them before Aaron the priest, that they may minister to him.
1 Chronicles 24:1
Now these are the divisions of the sons of Aaron. The sons of Aaron; Nadab, and Abihu, Eleazar, and Ithamar.
2 Chronicles 35:4-5
And prepare yourselves by the houses of your fathers after your courses, according to the writing of David king of Israel, and according to the writing of Solomon his son.
Numbers 8:9-26
And thou shalt bring the Levites before the tabernacle of the congregation: and thou shalt convene the whole assembly of the children of Israel:
1 Chronicles 23:1-26
So when David was old and full of days, he made Solomon his son king over Israel.