Proverbs 12:21-23 contain three instructive contrasts between the righteous and the wicked.
12:21--No harm happens to the righteous,
but the wicked are filled with trouble.
This statement does not naively shut the eye to the fact that bad things happen to good people or that good things happen to bad people, but is taking the long look at life. In the long haul, God blesses the righteous in multiple ways, but punishes the wicked in multiple ways.
12:22--Lying lips are an abomination to the Lord,
but those who act faithfully are his delight.
This proverb continues the emphasis on the importance of speaking the truth in verses 17 and 19. Sin is very serious, because it corrupts the sinner and spreads pain and sorrow throughout society. So God hates sin. It is an abomination to him, because he does not want his creatures to destroy themselves. It is a joy to him when people choose to speak and act faithfully.
12:23--One who is clever conceals knowledge,
but the mind of a fool broadcasts folly.
Picking up the idea already stated in verse 16, the poet declares that a fool is ready at any moment to state his/her opinion on any and every issue. By contrast, a wise or prudent [clever?] person quietly and wisely keeps silent until he/she has thought through the matter under discussion, and weighs the implications of several possible conclusions.