The World Federation One Stop Fiqh

Ruling 1578

If someone ascribes to Allah, Prophet Muḥammad (Ṣ), [or the Twelve Imams (ʿA)] something that he knows to be false, and afterwards he realises that what he said was true, and he knew that this act would invalidate his fast, he must, based on obligatory precaution, complete his fast and also keep a qaḍāʾ fast.