ANSWER:

If he said what he thought was right at the time, he made a mistake and it was unintentional.

If he can correct that information to those who were misinformed, that would be good.

Otherwise, there is no sin on him in Sha Allah as long as he had repented and showed remorse for speaking without proper knowledge.

QUESTION: If someone says something in Islam which he knows is most likely true but later finds out it was not true, has he done the major sin of lying against the prophet sallallahu alaihi wa sallam and Allah, what can he do if he falls in this situation?