حَدَّثَنَا مُحَمَّدُ بْنُ قُدَامَةَ بْنِ أَعْيَنَ، حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ هِلاَلٍ، - يَعْنِي ابْنَ يِسَافٍ - عَنْ أَبِي يَحْيَى، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ حُدِّثْتُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ صَلاَةُ الرَّجُلِ قَاعِدًا نِصْفُ الصَّلاَةِ ‏"‏ ‏.‏ فَأَتَيْتُهُ فَوَجَدْتُهُ يُصَلِّي جَالِسًا فَوَضَعْتُ يَدَىَّ عَلَى رَأْسِي فَقَالَ مَا لَكَ يَا عَبْدَ اللَّهِ بْنَ عَمْرٍو قُلْتُ حُدِّثْتُ يَا رَسُولَ اللَّهِ أَنَّكَ قُلْتَ ‏"‏ صَلاَةُ الرَّجُلِ قَاعِدًا نِصْفُ الصَّلاَةِ ‏"‏ ‏.‏ وَأَنْتَ تُصَلِّي قَاعِدًا قَالَ ‏"‏ أَجَلْ وَلَكِنِّي لَسْتُ كَأَحَدٍ مِنْكُمْ ‏"
Translation
‘Abd Allah b. ‘Amr said

It was narrated to me that the Messenger of Allah (ﷺ) said: "The prayer of a man sitting is half of the prayer." I came to him and found him praying sitting down, so I placed my hand on my head. He said: "What is the matter with you, O 'Abdullah bin 'Amr?" I said: "O Messenger of Allah, it was narrated to me that you said: 'The prayer of a man sitting is half of the prayer,' yet you are praying sitting down." He said: "Yes, but I am not like any of you."