Albert Barnes 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)

Son - The Hebrew word occurs here only and is therefore of doubtful meaning. The favored slave, petted and pampered from boyhood, will claim at last the privilege, perhaps the inheritance, of sonship.