In fact, there was a precept of the king about them, and an order among the singing men, throughout each day
Other versions
King James Version
For it was the king's commandment concerning them, that a certain portion should be for the singers, due for every day. English Standard Version
For there was a command from the king concerning them, and a fixed provision for the singers, as every day required.New International Version
The singers were under the king's orders, which regulated their daily activity.