'Courses' in the Bible

And it came to pass, when the priests were come out of the holy place, (for all the priests that were present had sanctified themselves, and did not keep their courses;

And he appointed, according to the ordinance of David his father, the courses 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 courses at every gate: for so had David the man of God commanded.

So the Levites and all Judah did according to all that Jehoiada the priest commanded: and they took every man his men, those that were to come in on the sabbath; with those that were to go out on the sabbath; for Jehoiada the priest dismissed not the courses.

And Hezekiah appointed the courses of the priests and the Levites after their courses, every man according to his service, both the priests and the Levites, for burnt-offerings and for peace-offerings, to minister, and to give thanks, and to praise in the gates of the camp of Jehovah.

And under him were Eden, and Miniamin, and Jeshua, and Shemaiah, Amariah, and Shecaniah, in the cities of the priests, in their office of trust, to give to their brethren by courses, as well to the great as to the small:

besides them that were reckoned by genealogy of males, from three years old and upward, even every one that entered into the house of Jehovah, as the duty of every day required, for their service in their offices according to their courses;

and them that were reckoned by genealogy of the priests by their fathers houses, and the Levites from twenty years old and upward, in their offices by their courses;

And prepare yourselves after your fathers houses by your courses, according to the writing of David king of Israel, and according to the writing of Solomon his son.

So the service was prepared, and the priests stood in their place, and the Levites by their courses, according to the king's commandment.