1 Chronicles 9:22-25

All these that were chosen to be porters in the thresholds were two hundred and twelve. These were reckoned by genealogy in their villages, whom David and Samuel the seer did ordain in their office of trust. So they and their children had the oversight of the gates of the house of Jehovah, even the house of the tent, by wards. On the four sides were the porters, toward the east, west, north, and south. And their brethren, in their villages, were to come in every seven days from time to time to be with them