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

Question:
Honorable Shaykh, there is a man who is traveling who prayed the night prayer behind a man who is traveling and praying the sunset prayer. He caught up with the second unit, then said the closing salam with the imam, and did not complete four units. What is the ruling on his prayer?

Answer:
Praying the night prayer behind the sunset prayer involves a problem and scholarly disagreement. Some scholars do not consider it valid to pray the night prayer or a four-unit prayer behind the sunset prayer, due to the difference in the form of the two prayers, and this is the correct view. So, does a person pray the sunset prayer first, or does he pray the night prayer? He should pray the night prayer alone or with a congregation of people like him, and not pray it behind someone who is praying the sunset prayer. He should pray the night prayer shortened, either alone or with travelers like him who shorten the prayer, and not pray it behind someone who is praying the sunset prayer, so that he avoids this problem regarding the form of the two prayers.