Is it permissible for a traveler to shorten the Asr prayer after having prayed the Dhuhr prayer in full in his hometown and departed it before the time for Asr began?

If a person prays Dhuhr in his city and then travels, it is not permissible for him to pray Asr before its time. Rather, he must wait until the time for Asr prayer arrives, then he can pray it shortened; because the entry of the time is a condition for the validity of the prayer, as Allah Almighty says: "Indeed, prayer has been decreed upon the believers a [properly] timed ordinance."