For the proper understanding and reconciliation between the two reports is that; whoever returns from his journey and the prayer time remains such that there is still enough time to complete (the prayer), then it is upon him to pray in full. But if he fears that the time will run out, then he must shorten (the prayer). Likewise is the ruling for one who sets out on a journey, if he fears that the time will be missed, then he shortens (the prayer); but if there is enough time remaining, he completes it. And what indicates that is what was narrated:
Commentary #15