The ruling on shortening the four-rak'ah prayer in a settled location due to rain

The questioner : What is your view regarding a man who led a group in the 'Isha' prayer on a rainy night, shortening the four-rak'ah prayer to two rak'ahs, while he was in a settled location?

The Shaykh : Yes. We hold that his prayer is invalid, and that it is obligatory for him now to pray four rak'ahs to make up for what he did, and that he must inform the congregation he led that they are required to pray the 'Isha' prayer as four rak'ahs now. This is because there is no reason for shortening the prayer other than travel. That is, illness permits combining prayers but does not permit shortening them, and rain permits combining prayers but does not permit shortening them. I recall that when I was ill, I asked you how to pray?
Likewise, a person should, when visiting a sick person, ask him how he prays and how he performs ritual purity, so that he can inform him of the Shari'ah if he is making a mistake. So this man said, "By Allah, for twenty days I have been, praise be to Allah, combining and shortening, while I am in my hometown." Does his statement that he combines agree with this or not? It agrees, because if it is difficult for a sick person to pray each prayer at its time, he may combine them. But his statement that he shortens is not agreed upon. What do we order this sick person to do?
We order him to repeat the prayer, to repeat the 'Isha' prayer specifically, because he prayed it as two rak'ahs, and it is obligatory for him to pray four. Likewise, the Zuhr and 'Asr prayers, if he was shortening them, it is obligatory for him to repeat them as four rak'ahs.