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 }  

“We were with Ibn ‘Umar on a journey, and he led us in prayer. Then we finished with him and he finished turning around, and saw some people praying. He said: ‘What are these people doing?’ I said: ‘Glorifying Allah.’* He said: ‘If I wanted to glorify Allah (perform voluntary prayer) I would have completed my prayer. O son of my brother! I accompanied the Messenger of Allah ﷺ and he never prayed more than two Rak’ah when he was traveling, until Allah took his soul. Then I accompanied Abu Bakr and he never prayed more than two Rak’ah (when he was traveling), until Allah took his soul. Then I accompanied ‘Umar and he never prayed more than two Rak’ah, until Allah took his soul. Then I accompanied ‘Uthman and he never prayed more than two Rak’ah, until Allah took his soul. Allah says: ‘Indeed in the Messenger of Allah (Muhammad ﷺ) you have a good example to follow.’” [33:21] * Meaning, they were offering voluntary prayer.  

مَا يَصْنَعُ هَؤُلاَءِ قُلْتُ يُسَبِّحُونَ قَالَ لَوْ كُنْتُ مُسَبِّحًا لأَتْمَمْتُ صَلاَتِي يَا ابْنَ أَخِي إِنِّي صَحِبْتُ رَسُولَ اللَّهِ ﷺ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ فِي السَّفَرِ حَتَّى قَبَضَهُ اللَّهُ ثُمَّ صَحِبْتُ أَبَا بَكْرٍ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ ثُمَّ صَحِبْتُ عُمَرَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ ثُمَّ صَحِبْتُ عُثْمَانَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُمُ اللَّهُ وَاللَّهُ يَقُولُ {لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللَّهِ أُسْوَةٌ حَسَنَةٌ }  

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" (Using translation from Abū Dāʾūd 1223)   

لَوْ كُنْتُ مُسَبِّحًا أَتْمَمْتُ صَلَاتِي يَا ابْنَ أَخَى إِنِّي صَحِبْتُ رَسُولَ اللهِ ﷺ فِي السَّفَرِ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللهُ وَصَحِبْتُ أَبَا بَكْرٍ ؓ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللهُ وَصَحِبْتُ عُمَرَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللهُ وَصَحِبْتُ عُثْمَانَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللهُ وَقَدْ قَالَ اللهُ ﷻ {لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللهِ أُسْوَةٌ حَسَنَةٌ} [الأحزاب 21]