I accompanied the Messenger of Allah ﷺ on eighteen journeys and I never saw him fail to pray two rak'ahs when the sun had passed the meridian before offering the noon prayer.  

صَحِبْتُ رَسُولَ اللَّهِ ﷺ ثَمَانِيَةَ عَشَرَ سَفَرًا فَمَا رَأَيْتُهُ تَرَكَ رَكْعَتَيْنِ إِذَا زَاغَتِ الشَّمْسُ قَبْلَ الظُّهْرِ  

I accompanied Ibn 'Umar on the way (on a journey). He led us in two rak'ah's of (the noon) prayer. Then he proceeded and saw some people standing. He asked: What are they doing ? I replied: They are glorifying Allah (i.e. offering supererogatory prayer). He said: If I had offered the supererogatory prayer (while travelling), I would have completed prayer, my cousin. I accompanied the Messenger of Allah ﷺ during the journey, he did not pray more than two raka'at until his death. I also accompanied Abu Bakr, and he prayed two raka'at and nothing more until he died. I also accompanied 'Umar, and he prayed two raka'at and nothing more until he died. I also accompanied 'Uthman, and he prayed two raka'at and nothing more until he died. Indeed Allah, the Exalted, said: "Certainly you have in the Messenger of Allah an excellent exemplar"  

لَوْ كُنْتُ مُسَبِّحًا أَتْمَمْتُ صَلاَتِي يَا ابْنَ أَخِي إِنِّي صَحِبْتُ رَسُولَ اللَّهِ ﷺ فِي السَّفَرِ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ ﷻ وَصَحِبْتُ أَبَا بَكْرٍ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ ﷻ وَصَحِبْتُ عُمَرَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ تَعَالَى وَصَحِبْتُ عُثْمَانَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ تَعَالَى وَقَدْ قَالَ اللَّهُ ﷻ { لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللَّهِ أُسْوَةٌ حَسَنَةٌ }