2 Chronicles 31:17

And the enrolling of the priests for the house of their fathers, and the Levites from the son of twenty years and above, in their watches, by their divisions:

1 Chronicles 23:24

These the sons of Levi for the house of their fathers: the heads of the fathers for their reviewing by the number of names to their craniums doing the work for the service of the house of Jehovah, from the son of twenty years and above.

1 Chronicles 23:27

For by the last words of David these the number of the sons of Levi from the son of twenty years and above.

Numbers 3:15

Review the sons of Levi according to the house of their fathers, according to their families: every male from the son of a month and above shalt thou review them.

Numbers 3:20

And the sons of Merari according to their families: Mahli, and Mushi; these they of the families of the Levites according to the house of their fathers.

Numbers 4:3

From the son of thirty years and above, and to the son of fifty years, all coming in to war to do the works of the tent of appointment

Numbers 4:38

And they being reviewed of the sons of Gershon, according to their families, according to the house of their fathers,

Numbers 4:42

And they being reviewed of the families of the sons of Merari, according to their families, according to the house of their fathers,

Numbers 4:46

All the reviewings which Moses reviewed, and Aaron, and the chiefs of Israel, the Levites, according to their families, and according to the house of their fathers,

Numbers 8:24

This is that to the Levites: from the son of five and twenty years and above, and he came in to war the warfare in serving the tent of appointment

Numbers 17:2-3

Speak to the sons of Israel, and take from them a rod, a rod according to the house of the father, from all the chiefs according to the house of their fathers, twelve rods: thou shalt write each his name upon his rod.

1 Chronicles 24:20-26

And to the sons of Levi remaining: To the sons of Amram: Shubael: to the sons of Shubael, Jehdeiah.

2 Chronicles 31:2

And Hezekiah will set up the divisions of the priests and the Levites for their divisions each according to the mouth of his service to the priests and to the Levites for the burnt-offering and for the peace, to serve and to confess and to praise, in the gates of the camp of Jehovah.

Ezra 2:59

And these going up from Tel-Me-lah Tel-Harsa, Cherub, Addan, Immer and they were not able to announce their father's house, and their seed, if they were from Israel.

Treasury of Scripture Knowledge

Summary

Both to the genealogy of the priests by the house of their fathers, and the Levites from twenty years old and upward, in their charges by their courses;

Bible References

Genealogy

Numbers 3:15
Review the sons of Levi according to the house of their fathers, according to their families: every male from the son of a month and above shalt thou review them.
Numbers 4:38
And they being reviewed of the sons of Gershon, according to their families, according to the house of their fathers,
Numbers 17:2
Speak to the sons of Israel, and take from them a rod, a rod according to the house of the father, from all the chiefs according to the house of their fathers, twelve rods: thou shalt write each his name upon his rod.
Ezra 2:59
And these going up from Tel-Me-lah Tel-Harsa, Cherub, Addan, Immer and they were not able to announce their father's house, and their seed, if they were from Israel.

Twenty

Numbers 4:3
From the son of thirty years and above, and to the son of fifty years, all coming in to war to do the works of the tent of appointment
Numbers 8:24
This is that to the Levites: from the son of five and twenty years and above, and he came in to war the warfare in serving the tent of appointment
1 Chronicles 23:24
These the sons of Levi for the house of their fathers: the heads of the fathers for their reviewing by the number of names to their craniums doing the work for the service of the house of Jehovah, from the son of twenty years and above.

By their courses

2 Chronicles 31:2
And Hezekiah will set up the divisions of the priests and the Levites for their divisions each according to the mouth of his service to the priests and to the Levites for the burnt-offering and for the peace, to serve and to confess and to praise, in the gates of the camp of Jehovah.
1 Chronicles 24:20
And to the sons of Levi remaining: To the sons of Amram: Shubael: to the sons of Shubael, Jehdeiah.