He and Ibn ‘Umar said that God’s Messenger established the practice of praying two <i>rak'as</i> when travelling, they constituting a complete observance and not an abbreviation; and the <i>witr</i> while travelling is a <i>sunna</i>. Ibn Majah transmitted it.

وَعَن ابْن عَبَّاس وَعَنِ ابْنِ عُمَرَ قَالَا: سَنَّ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ صَلَاةَ السَّفَرِ رَكْعَتَيْنِ وَهُمَا تَمَامٌ غَيْرُ قَصْرٍ وَالْوِتْرُ فِي السَّفَرِ سنة. رَوَاهُ ابْن مَاجَه