Is it permissible for a traveler to combine the Maghrib and Isha prayers by delaying the Maghrib prayer to be performed with the Isha prayer (Jam’ Takhir), half an hour before the Isha Adhan, based on the understanding that the time for Isha extends until the true dawn, as stated by Ibn Taymiyyah?

The madhhab of Sheikh al-Islam Ibn Taymiyyah agrees with the Hanbali madhhab in dividing the time for Isha prayer into a time of choice (waqt ikhtiyar) that extends until midnight, and a time of necessity (waqt darurah) that extends until Fajr. It is not permissible to delay Isha prayer until the time of necessity except for an excuse. These excuses are of two types: excuses that permit combining prayers (such as travel, illness, and rain), and excuses that remove sin from the one who delays if he performs the prayer during the time of necessity due to being unable to perform it during the time of choice (such as a menstruating woman who becomes pure, or a sleeper who wakes up). So, a traveler for whom travel permits combining prayers is not allowed to delay Isha past midnight unless another excuse that permits delaying for necessity, like sleep, also applies.