'Mistress' in the Bible

He slept with Hagar, and she became pregnant. When she realized that she was pregnant, she treated her mistress with contempt.

He said, “Hagar, slave of Sarai, where have you come from and where are you going?”She replied, “I’m running away from my mistress Sarai.”

Then the Angel of the Lord said to her, “You must go back to your mistress and submit to her mistreatment.”