Verses with the word mistress in the Old Testament (9 verses):

Genesis 16:4
And he went in unto Hagar, and she conceived: and when she saw that she had conceived, her mistress was despised in her eyes.

Genesis 16:8
And he said, Hagar, Sarai's maid, whence camest thou? and whither wilt thou go? And she said, I flee from the face of my mistress Sarai.

Genesis 16:9
And the angel of the LORD said unto her, Return to thy mistress, and submit thyself under her hands.

1 Kings 17:17
And it came to pass after these things, that the son of the woman, the mistress of the house, fell sick; and his sickness was so sore, that there was no breath left in him.

2 Kings 5:3
And she said unto her mistress, Would God my lord were with the prophet that is in Samaria! for he would recover him of his leprosy.

Psalms 123:2
Behold, as the eyes of servants look unto the hand of their masters, and as the eyes of a maiden unto the hand of her mistress; so our eyes wait upon the LORD our God, until that he have mercy upon us.

Proverbs 30:23
For an odious woman when she is married; and an handmaid that is heir to her mistress.

Isaiah 24:2
And it shall be, as with the people, so with the priest; as with the servant, so with his master; as with the maid, so with her mistress; as with the buyer, so with the seller; as with the lender, so with the borrower; as with the taker of usury, so with the giver of usury to him.

Nahum 3:4
Because of the multitude of the whoredoms of the wellfavoured harlot, the mistress of witchcrafts, that selleth nations through her whoredoms, and families through her witchcrafts.