Verses with the word conceit in the Old Testament (5 verses):

Proverbs 18:11
The rich man's wealth is his strong city, and as an high wall in his own conceit.

Proverbs 26:5
Answer a fool according to his folly, lest he be wise in his own conceit.

Proverbs 26:12
Seest thou a man wise in his own conceit? there is more hope of a fool than of him.

Proverbs 26:16
The sluggard is wiser in his own conceit than seven men that can render a reason.

Proverbs 28:11
The rich man is wise in his own conceit; but the poor that hath understanding searcheth him out.