What is the ruling on praying Maghrib before its time when traveling, given that the worshipper will not be able to perform it at its [prescribed] time, as he will return after the ‘Isha’ call to prayer by a period [of time]?

The Lawgiver permitted the traveler to combine two prayers sharing the same time, either by performing them early (collection by advancing) if he departs after the entry of the time of the first prayer, or by delaying them (collection by delaying) if he departs before the entry of its time, as a facilitation for him. For Al-Bukhari and Muslim reported from Anas that the Prophet, peace and blessings be upon him, "If he departed before the sun declined, he would delay the Dhuhr prayer until the time of the Asr prayer, then combine them. But if the sun declined before he departed, he would pray Dhuhr, then mount."