It was narrated from ‘Abdullah bin ‘Amr that the Prophet (ﷺ) passed by him when he was praying sitting down. He said:“The prayer of one who sits down is equivalent to half of the prayer of one who stands.”
حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا يَحْيَى بْنُ آدَمَ، حَدَّثَنَا قُطْبَةُ، عَنِ الأَعْمَشِ، عَنْ حَبِيبِ بْنِ أَبِي ثَابِتٍ، عَنْ عَبْدِ اللَّهِ بْنِ بَابَاهْ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ مَرَّ بِهِ وَهُوَ يُصَلِّي جَالِسًا فَقَالَ " صَلاَةُ الْجَالِسِ عَلَى النِّصْفِ مِنْ صَلاَةِ الْقَائِمِ " .
IbnMaja
Establishing the Prayer and the Sunnah Regarding Them • Hadith 1229