Beware of "Had I wist."

The proverb urges care before a decision. Finding out something important afterward may leave a person regretting what they did.

Its warning is directed at avoidable regret: ask questions, consider consequences, and make use of what you can learn while there is still time to act.

Use it to encourage someone to check the facts or weigh a choice before committing to it, especially when a later discovery would be difficult to put right.