Is it obligatory to repeat an act of worship that one is certain was invalid?

The questioner : In the hadith, we said that the prayer is repeated; for this reason, he was not commanded to repeat it. Should we not benefit from this by saying that if it becomes clear that a person’s act of worship, such as fasting or something similar, was invalid, he is not commanded to repeat it except for what does not repeat? As for what does repeat, he is not commanded to repeat it.

The Shaykh : No, if we know from the Qur’an, repetition is obligatory. But this is not a place for obligation in the first place, meaning that a barrier to obligation was found in it, which is menstruation.