'Locked' in the Bible

Now when he had gone, the king's servants came, and saw that the doors of the summer-house were locked; and they said, It may be that he is in his summer-house for a private purpose.

And news was given to Saul that David had come to Keilah. And Saul said, Now God has given him into my hands; for by going into a walled town with locked doors, he has let himself be shut in.

Then he gave a cry to the servant who was waiting on him and said, Put this woman out, and let the door be locked after her.

And I said to them, Do not let the doors of Jerusalem be open till the sun is high; and while the watchmen are in their places, let the doors be shut and locked: and let the people of Jerusalem be put on watch, every one in his watch, opposite his house.

A brother wounded is like a strong town, and violent acts are like a locked tower.