These were the groups chosen to serve in the Temple of the Lord. They obeyed the rules given them by Aaron, just as the Lord, the God of Israel, had commanded him.
The gatekeepers’ relatives who lived in the villages had to come and help them at times. Each time they came they helped the gatekeepers for seven days.
The Levites and all the people of Judah obeyed everything Jehoiada the priest had commanded. He did not excuse anyone from the groups of the priests. So each commander took his men who came on duty on the Sabbath with those who went off duty on the Sabbath.
The people were given the law concerning the system of priests from the tribe of Levi, but they could not be made perfect through that system. So there was a need for another priest to come, a priest like Melchizedek, not Aaron.