The ruling on praying Maghrib behind an imam who is praying 'Isha'

Question:
May Allah reward you. The questioner says: I was traveling from one area to the area where I reside. I attended the Maghrib prayer, but it was delayed and combined with 'Isha'. I arrived in my area at the time of the 'Isha' prayer and joined the imam after missing one rak'ah, intending to pray Maghrib. When he said the taslim, I said it with him, and then I prayed 'Isha' for four rak'ahs. Is my action valid?

Answer:
It is valid, if Allah wills, according to your intention. Indeed, actions are by intentions. You intended it to be Maghrib, so you prayed behind the imam who was praying 'Isha'. You get what you intended. You did not add to Maghrib by adding a fourth rak'ah, so you get what you intended. Your prayer is valid. Indeed, actions are by intentions, and every person gets what he intended.