Matthew Henry Commentary Proverbs 29:21

"He that delicately bringeth up his servant from a child Shall have him become a son at the last." — Proverbs 29:21 (ASV)

Proper treatment of a servant does not mean indulgence, which would ruin even a child. The body is a servant to the soul; those who indulge it and are excessively gentle with it will find it forgets its place.