عَنِ ابْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُ قَالَ: سَنَّ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ الصَّلَاةَ فِي السَّفَرِ رَكْعَتَيْنِ وَهِيَ تَمَامٌ وَالْوِتْرُ فِي السَّفَرِ سُنَّةٌ
Abdullah bin Abbas (may Allah be pleased with him) says: The Messenger of Allah (peace and blessings be upon him) prescribed two rak'ahs of prayer during travel, and this is the complete prayer, and offering Witr during travel is Sunnah.