Matthew Henry Commentary Proverbs 30:21-23

"For three things the earth doth tremble, And for four, [which] it cannot bear: For a servant when he is king; And a fool when he is filled with food; For an odious woman when she is married; And a handmaid that is heir to her mistress." — Proverbs 30:21-23 (ASV)

Four types of people are very troublesome:

1. Men of low origin and base spirit, who, once they gain authority, become tyrants.
2. Foolish and violent men indulging in excesses.
3. A woman of a contentious spirit and vicious habits.
4. A servant who has obtained undue influence.

Let those whom Providence has advanced from humble beginnings carefully watch against that sin which most easily besets them.