Ecclesiastes 10:7
"I have seen servants upon horses, and princes walking as servants upon the earth."
Cross References (ranked by relevance)
Proverbs 19:10
Delight is not seemly for a fool; much less for a servant to have rule over princes.
Esther 6:8
Let the royal apparel be brought which the king useth to wear, and the horse that the king rideth upon, and the crown royal which is set upon his head:
Proverbs 30:22
For a servant when he reigneth; and a fool when he is filled with meat;