عَنْ أَنَسٍ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُفْطِرُ مِنَ الشَّهْرِ حَتَّى يُظَنَّ أَنْ لَا يَصُومَ مِنْهُ وَيَصُومُ حَتَّى يُظَنَّ أَنْ لَا يُفْطِرَ مِنْهُ شَيْئًا وَكَانَ لَا تَشَاءُ أَنْ تَرَاهُ مِنَ اللَّيْلِ مُصَلِّيًا إِلَّا رَأَيْتَهُ وَلَا نَائِمًا إِلَّا رَأَيْتَهُ. 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.