How do we distinguish between the one accused of lying and the one who made a mistake?

The Shaykh : Yes, the difference between them lies in what is in the speaker's heart. For example, if someone tells us that so-and-so has arrived, and he knows that he has not arrived, then he is a disbeliever. As for us, if this man is known for lying, we know that he is lying and we do not believe him. And if he is known for truthfulness, but we do not find the man he reported to be present, we say that this is the better opinion.