When I am travelling, I combine and shorten the prayer, so what should I do if the time for Maghrib prayer started whereas I had not yet offered the Thuhr and ‘Asr prayers? Do I have to offer four Rak‘ahs or two?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

The one who travels for a distance that permits him to use the concession of shortening the prayer, can shorten the four Rak‘ah-prayer into two Rak‘ahs but the Fajr and Maghrib prayers cannot be shortened. He is permitted to combine the two prayers in the time of one of them so he combines Thuhr and `Asr, and combines Maghrib and ‘Ishaa’. He is not ever permitted to delay offering the day time prayers until the night or vice versa. For instance: delaying offering Thuhr and ‘Asr until he offers them with Maghrib and ‘Ishaa’ or delaying offering Maghrib and ‘Ishaa’ to offer them with Fajr. This is prohibited according to the consensus of scholars. Rather, he is to offer the daytime prayers in the daytime and the night prayers in the night regardless of his conditions.

If it happened that the traveler delayed Thuhr and ‘Asr until the Maghrib time started, he is to make up Thuhr then ‘Asr in the shortened form (two Rak‘ahs) if he was travelling whereas he offers them in the full form in the state of residency, and then he offers Maghrib.

So, he makes up for the prayers in the same order of offering them unless he fears that the current prayer time will elapse, then he has to offer it during its due time so that he does not miss two prayers.