Proverbs 24:9

9The thought of foolishness is sin: and the scorner is an abomination to men.

1 Corinthians 1:18

18For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.

1 Corinthians 3:19

19For the wisdom of this world is foolishness with God. For it is written, He taketh the wise in their own craftiness.

Proverbs 10:14

14Wise men lay up knowledge: but the mouth of the foolish is near destruction.

Psalms 69:5

5O God, thou knowest my foolishness; and my sins are not hid from thee.

Proverbs 12:23

23A prudent man concealeth knowledge: but the heart of fools proclaimeth foolishness.

Proverbs 14:24

24The crown of the wise is their riches: but the foolishness of fools is folly.

Proverbs 15:2

2The tongue of the wise useth knowledge aright: but the mouth of fools poureth out foolishness.

Proverbs 15:14

14The heart of him that hath understanding seeketh knowledge: but the mouth of fools feedeth on foolishness.

Proverbs 19:3

3The foolishness of man perverteth his way: and his heart fretteth against the LORD.

(Special thanks to Doctrine Matters Bible Topic Guidebook by Missionary spencer smith.)