Mishkat al-Masabih 4 Prayer كتاب الصلاة 664

وَعَن عمرَان بن حُصَيْن: أَنَّهُ سَأَلَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنْ صَلَاةِ الرَّجُلِ قَاعِدًا. قَالَ: «إِنْ صَلَّى قَائِمًا فَهُوَ أَفْضَلُ وَمَنْ صَلَّى قَاعِدًا فَلَهُ نِصْفُ أَجْرِ الْقَائِمِ وَمَنْ صَلَّى نَائِمًا فَلَهُ نصف أجل الْقَاعِد» . رَوَاهُ البُخَارِيّ

He said he asked the Prophet about a man who prays sitting, and he replied, “If he prays standing that is more excellent; but one who prays sitting has half the reward of one who stands, and one who prays lying down has half the reward of one who sits.” Bukhari transmitted it.