'Minister' in the Bible

Also the firstborn of our sons, and of our cattle, as it is written in the law, and the firstlings of our herds and of our flocks, to bring to the house of our God, unto the priests that minister in the house of our God:

For the children of Israel and the children of Levi shall bring the offering of the corn, of the new wine, and the oil, unto the chambers, where are the vessels of the sanctuary, and the priests that minister, and the porters, and the singers: and we will not forsake the house of our God.