C. F. Keil and Franz Delitzsch on 1 Chronicles 9:27

1Ch 9:27 1Ch 9:27 refers again to the doorkeepers. They passed the night around the house of God, because the care of or watch over it was committed to them, and “they were over the key, and that every morning,” i.e., they had to open the door every morning. מפתּח occurs again in Jdg 3:25 and Isa 22:22, in the signification key, which is suitable here also.