One of the frustrating things about mistakes is that they don’t help much. When we fail to follow through on a promise, the excuse of “it was an innocent mistake!” doesn’t seem to help in getting us out of trouble. As Solomon, the wisest of all men, wrote regarding making financial commitments and promises:
It’s better that you not make a promise than to promise and then not pay. Don’t let your mouth bring sin upon your flesh; don’t tell the collector that it was just a mistake. Why should G-d grow angry because of your voice and destroy the work of your hands? (Ecc. 5:5-6).
Note, Solomon gives us two pieces of advice: the first is that it’s better for us to humbly admit when we aren’t sure we can really do what is being asked of us. This may be frustrating for someone asking a favor but it won’t be as annoying as when we don’t actually follow through.
The second piece of advice is to just own up to whatever we’ve done. The tax collector won’t have sympathy when we tell him it was just a mistake, and we shouldn’t expect that anyone else will either.