'Ata' said, "Ibn 'Umar visited Ibn Safwan and the time came for the prayer. So Ibn 'Umar prayed two rak'ats with them and then observed, 'I am travelling.'"  

عَنْ عَطَاءٍ قَالَ عَادَ ابْنُ عُمَرَ ابْنَ صَفْوَانَ فَحَضَرَتِ الصَّلاَةُ فَصَلَّى بِهِمُ ابْنُ عُمَرَ رَكْعَتَيْنِ وَقَالَ إِنَّا سَفْرٌ