Backbiting is not just a mistake by the speaker; it can harm the honour and rights of the person being discussed. That is why “it was only a few words” does not settle the matter.
A person should regret the wrong, stop it, and seek to repair harm where possible. Preventing further circulation, correcting a harmful claim, and guarding future speech are practical parts of improvement.
Example: A mocking message about a classmate spreads around a group. Deleting it is a useful first step; the sender should also consider how to reduce the damage and avoid repeating it.