An honest factual mistake and a deliberate lie are not the same. Yet once a mistake is discovered, refusing to correct it or continuing to exploit someone's reliance can deepen the harm.
Example 1: A person gives an incorrect date and promptly corrects it after checking.
Example 2: A person knowingly gives a false date so another party will suffer a loss. That is deception.
حَدِيثًا here means a statement or report; it is not restricted to the technical meaning of a Prophetic hadith. The suffix كَ in أَخَاكَ means “your.”