Should I pray four rak'ahs of 'Isha prayer with the congregation in the mosque, or pray two rak'ahs individually and then continue my journey?

Congregational prayer is obligatory for men, whether they are residents or travelers. If there is a congregation of travelers, the traveler should pray with them, shortening the prayer. Otherwise, he should pray with the residents, completing the four rak'ahs. The proof of its obligation for the traveler is Allah’s command concerning it during wartime, in His saying: "And when you are among them and lead them in prayer, let a group of them stand with you and let them take their weapons. Then when they have prostrated, let them be behind you, and let another group who have not prayed come forward and pray with you." Therefore, a traveler must attend congregational prayer in the mosque if he hears the call, unless he is far away or fears missing his companions.