The ruling on one who missed the Maghrib prayer and found a congregation praying the 'Isha' prayer

Question:
He says: Honorable Shaykh, what is the manner of prayer for one who missed the Maghrib prayer and coincided with the 'Isha' prayer congregation, such as if he were a traveler who combined the Maghrib and 'Isha' prayers, and upon entering the 'Isha' prayer he found a congregation praying the 'Isha' prayer from the beginning of the prayer?

Answer:
If he has already prayed the Maghrib, he joins them in the 'Isha', and the combination is realized for him. He prays the Maghrib first, then joins the congregation who are praying the 'Isha', and he prays it immediately after the Maghrib; this is the combination. As for if his intention is to join them in the 'Isha' prayer with the intention of the Maghrib, this is not permissible due to the difference between the two prayers, the four-unit and the three-unit. He prays the Maghrib first, then joins them in the remainder of the 'Isha' prayer and completes it after the 'Isha' prayer. Yes.