The Ruling on Praying 'Isha' with the Imam of Tarawih

Question : He says: What is your opinion regarding those who pray the 'Isha' prayer in a mosque at the time when the congregation of the mosque is praying the tarawih prayer? May Allah reward you.

Answer : We say that if a person enters while the imam is praying tarawih, he should enter with him intending to pray 'Isha', if Allah wills. Then, if he is a traveler, he prays two rak'ahs; and if he is a resident, he completes his prayer after the imam's taslim. An example of this is a traveler, a man in Makkah performing 'Umrah, who enters while the imam is praying tarawih. He joins him in the first rak'ah with the intention of 'Isha. We tell him to say the taslim with the imam, and his 'Isha prayer is complete, because he is a traveler, and the prayer of the traveler for the four-rak'ah prayer is two rak'ahs. As for if he is a resident, such as if a person enters while the people are praying the tarawih prayer in his hometown and joins them in the first rak'ah, we say: when the imam says the taslim, complete two rak'ahs.
This is what is best. As for some people separating with their own congregation in one part of the mosque while the people are praying, this is dividing the community.