Albert Barnes Commentary Proverbs 26:6

"He that sendeth a message by the hand of a fool Cutteth off [his own] feet, [and] drinketh in damage." — Proverbs 26:6 (ASV)

Cuts off the feet - Mutilates him, spoils the work which the messenger should fulfill.

Drinks damage - i.e., “has to drink full drafts of shame and loss” .