Is it permissible for a traveler to shorten some prayers and complete others during their journey?

Shortening prayers during travel is a Sunnah, not an obligation, and it is permissible to pray in full. However, shortening is better due to the continuous practice of the Prophet (peace be upon him) in doing so. It has been narrated that a number of companions completed their prayers during travel, and this is the view of Al-Awza'i, Al-Shafi'i, and the well-known opinion of Malik.