This verse is about making really dumb decisions. In antiquity, I wouldn’t be surprised if someone laughed whenever this wise saying was quoted.
“Cutting off one’s feet or drinking poison” is, of course, nothing a sane person would consider doing. But such insane activities are offered in simile to “sending a message by the hands of a fool.”
One of the most discussed characters in Proverbs, the “fool” is not someone who is mentally deficient. Instead, the fool is someone who doesn’t consider God to be a factor in their life (Psalms 14:1).
Such a mindset creates significant barriers for us to do the things we should do or be the person we can be. If I have an important message or critical business that needs to be done, I really should have confidence in the person to whom I give it.
We shouldn’t consider cutting off our own feet or drinking poison as a good idea. But there is a very good chance some of us might trust some fool with an important task today.
This verse suggests we better consider it very carefully. Don’t drink that poison, don’t whack off that body part and, maybe, its best I don’t trust that guy or gal!