What is the ruling on a traveler combining the Maghrib and 'Isha prayers by delaying Maghrib until the time of 'Isha (jama' ta'kheer), if he intended to do so, then arrived in his country after the 'Isha prayer time had begun, but he does not know whether the 'Isha time began before or after his arrival?

If a traveler intends to combine two prayers by delaying the first (jama' ta'khir), then arrives home during the time of the first prayer, the excuse for combining prayers is removed, and it becomes obligatory for him to pray each prayer precisely within its own time. This is because the condition for the permissibility of combining prayers is the continuation of the excuse until the entry of the time of the second prayer. If he combines them while violating this condition, his combining is invalid. However, if he combines them while the condition is met, it is valid.