Narrated Jabir bin ‘Abdullah:
Mu’adh used to pray with the Prophet and then go and lead his people (tribe) in the prayer.
Prophet (SAW) used to lead the prayer. Mu`adh (RA) prayed behind him, learnt his ways. Then he used to go back to his own tribe and lead them in the same prayer. So he used to pray (for instance) `Ishaa’ twice? :O
Not really. One can do as Mu`adh did, and make intention for nafl prayer. So if you prayed the `Ishaa’ prayer in a mosque, then you go somewhere and people ask you to lead them in `Ishaa’ prayer because you are the most knowledgeable among them, you may do so. Just make the intention that these four rak`aat will be nafl on your part and fardh for the rest.
Question: why did Mu`adh go through the trouble? Couldn’t someone else lead the prayer in his tribe?
Well, no one else was as knowldgeable and as wise as Mu`adh (RA). And he was among the tribe chieftain as well. So he had to be the Imaam of the masjid there as well. That’s how it was back then. Ministers in parliament were Imaams in the masjid. <3
You. Learn, and then lead. The process goes on in a cycle. You can never learn enough. So keep at it! :)