حَدَّثَنَا الْقَعْنَبِيُّ، حَدَّثَنَا عِيسَى بْنُ حَفْصِ بْنِ عَاصِمِ بْنِ عُمَرَ بْنِ الْخَطَّابِ، عَنْ أَبِيهِ، قَالَ صَحِبْتُ ابْنَ عُمَرَ فِي طَرِيقٍ - قَالَ - فَصَلَّى بِنَا رَكْعَتَيْنِ ثُمَّ أَقْبَلَ فَرَأَى نَاسًا قِيَامًا فَقَالَ مَا يَصْنَعُ هَؤُلاَءِ قُلْتُ يُسَبِّحُونَ ‏.‏ قَالَ لَوْ كُنْتُ مُسَبِّحًا أَتْمَمْتُ صَلاَتِي يَا ابْنَ أَخِي إِنِّي صَحِبْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم فِي السَّفَرِ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ عَزَّ وَجَلَّ وَصَحِبْتُ أَبَا بَكْرٍ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ عَزَّ وَجَلَّ وَصَحِبْتُ عُمَرَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ تَعَالَى وَصَحِبْتُ عُثْمَانَ فَلَمْ يَزِدْ عَلَى رَكْعَتَيْنِ حَتَّى قَبَضَهُ اللَّهُ تَعَالَى وَقَدْ قَالَ اللَّهُ عَزَّ وَجَلَّ ‏{‏ لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللَّهِ أُسْوَةٌ حَسَنَةٌ ‏}‏ ‏.‏

Narrated Hafs b. 'Asim: 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 (PBUH) 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" Translation Not Available

Book Ref: Sunan Abi Dawud Book 4 Hadith 1223
Web Ref:  Sunan Abi Dawud Book 4 Hadith 1219