1 Chronicles 9:25

He commanded them, saying, “This is what you must do: a third of you, who come in on the Sabbath, shall be keepers of the watch of the king’s house;

Now while he executed the priest’s office before God in the order of his division

This was their ordering in their service, to come into Yahweh’s house according to the ordinance given to them by Aaron their father, as Yahweh, the God of Israel, had commanded him.

The captains over hundreds did according to all that Jehoiada the priest commanded; and they each took his men, those who were to come in on the Sabbath, with those who were to go out on the Sabbath, and came to Jehoiada the priest.

So the Levites and all Judah did according to all that Jehoiada the priest commanded: and they each took his men, those who were to come in on the Sabbath; with those who were to go out on the Sabbath; for Jehoiada the priest didn’t dismiss the shift.

There was in the days of Herod, the king of Judea, a certain priest named Zacharias, of the priestly division of Abijah. He had a wife of the daughters of Aaron, and her name was Elizabeth.

When the days of his service were fulfilled, he departed to his house.

the food of his table, the sitting of his servants, the attendance of his officials, their clothing, his cup bearers, and his ascent by which he went up to Yahweh’s house; there was no more spirit in her.

The two companies of you, even all who go out on the Sabbath, shall keep the watch of Yahweh’s house around the king.

He took the captains over hundreds, and the Carites, and the guard, and all the people of the land; and they brought down the king from Yahweh’s house, and came by the way of the gate of the guard to the king’s house. He sat on the throne of the kings.

He removed the covered way for the Sabbath that they had built in the house, and the king’s entry outside to Yahweh’s house, because of the king of Assyria.

and that they should keep the duty of the Tent of Meeting, the duty of the holy place, and the duty of the sons of Aaron their brothers, for the service of Yahweh’s house.

These were the divisions of the sons of Aaron. The sons of Aaron: Nadab, Abihu, Eleazar, and Ithamar.

He appointed, according to the ordinance of David his father, the divisions of the priests to their service, and the Levites to their offices, to praise and to minister before the priests, as the duty of every day required; the doorkeepers also by their divisions at every gate, for David the man of God had so commanded.

This is the thing that you must do. A third part of you, who come in on the Sabbath, of the priests and of the Levites, shall be gatekeepers of the thresholds.

But let no one come into Yahweh’s house, except the priests and those who minister of the Levites. They shall come in, for they are holy, but all the people shall follow Yahweh’s instructions.

Hezekiah appointed the divisions of the priests and the Levites after their divisions, every man according to his service, both the priests and the Levites, for burnt offerings and for peace offerings, to minister, to give thanks, and to praise in the gates of Yahweh’s camp.

He set the priests in their offices, and encouraged them in the service of Yahweh’s house.

When the princes of Judah heard these things, they came up from the king’s house to Yahweh’s house; and they sat in the entry of the new gate of Yahweh’s house.

Let all things be done decently and in order.

Aren’t they all serving spirits, sent out to do service for the sake of those who will inherit salvation?

Now if perfection was through the Levitical priesthood (for under it the people have received the law), what further need was there for another priest to arise after the order of Melchizedek, and not be called after the order of Aaron?