Shut or close the barn door after the horse has bolted

Shut the barn door after the horse has bolted and close the barn door after the horse has bolted are versions of an idiom that has been in use for hundreds of years. An idiom is a commonly used word, group of words, or phrase that has a figurative meaning that is not easily deduced […]
from Grammarist
https://grammarist.com/idiom/shut-or-close-the-barn-door-after-the-horse-has-bolted/