Hafs b. ‘Asim said:

I accompanied Ibn ‘Umar on the road to Mecca and he led us in two <i>rak'as</i> at the noon prayer, then went to the place where he had alighted and sat down. Seeing some people standing he asked what they were doing, and I replied that they were engaged in glorifying God. He said, “If I had done so I would have perfected my prayer. I accompanied God's Messenger, and he prayed two <i>rak'as</i> and nothing more while on a journey. I also accompanied Abu Bakr, ‘Umar and ‘Uthman, and they did the same." (Bukhari and Muslim.)

وَعَنْ حَفْصِ بْنِ عَاصِمٍ قَالَ: صَحِبْتُ ابْنَ عُمَرَ فِي طَرِيقِ مَكَّةَ فَصَلَّى لَنَا الظُّهْرَ رَكْعَتَيْنِ ثُمَّ جَاءَ رَحْلَهُ وَجَلَسَ فَرَأَى نَاسًا قِيَامًا فَقَالَ: مَا يَصْنَعُ هَؤُلَاءِ؟ قُلْتُ: يُسَبِّحُونَ. قَالَ: لَوْ كُنْتُ مُسَبِّحًا أَتْمَمْتُ صَلَاتِي. صَحِبْتُ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَكَانَ لَا يَزِيدُ فِي السَّفَرِ عَلَى رَكْعَتَيْنِ وَأَبَا بكر وَعمر وَعُثْمَان كَذَلِك