The ruling on one who prays 'Isha' before Maghrib in a combined prayer while forgetting

Question:
I was traveling and intended to pray Maghrib and 'Isha' together as a final congregation. I arrived during the 'Isha' prayer. Then I entered the mosque, but I prayed 'Isha'. Maghrib. Then I remembered that in the sixth rak'ah, but I continued with the people in the witr. When I finished the prayer, I prayed Maghrib again, then the witr.

Answer:
I know that your action was a mistake. It is obligatory that when you realized you had not prayed Maghrib, you should have separated yourself; you separated yourself and prayed while the people were praying for themselves. The imam offered the prayer, then he would pray with them, and you would pray Maghrib first, then you would pray 'Isha'. But since the matter had passed and you did this out of ignorance, your extra prayer is valid, if Allah wills, and the prayer of the ma'mum is valid because they did not know about it. It may be that if you remember the prayer and there is ample time, you intend to make it up and complete it, and when you finish the taslim, you stand and pray Maghrib, then you pray 'Isha' after it.