[Machine] Imran ibn Husain asked the Messenger of Allah ﷺ about praying while sitting, and he ﷺ said, "Whoever prays while standing, it is better for him. And whoever prays while sitting, he will have half the reward of the one who prays while standing. And whoever prays while lying down, he will have half the reward of the one who prays while sitting."  

عَنْ عِمْرَانَ بْنِ حُصَيْنٍ سُئِلَ رَسُولُ اللهِ ﷺ عَنْ صَلَاةِ الْقَاعِدِ فَقَالَ ﷺ مَنْ صَلَّى قَائِمًا فَهُوَ أَفْضَلُ وَمَنْ صَلَّى قَاعِدًا فَلَهُ نِصْفُ أَجْرِ الْقَائِمِ وَمَنْ صَلَّى نَائِمًا فَلَهُ نِصْفُ أَجْرِ الْقَاعِدِ  

I heard Anas saying, "A man from Ansar said to the Prophet, 'I cannot pray with you (in congregation).' He was a very fat man and he prepared a meal for the Prophet ﷺ and invited him to his house. He spread out a mat for the Prophet, and washed one of its sides with water, and the Prophet ﷺ prayed two rakʿat on it." A man from the family of Al-Jaruid [??] asked, "Did the Prophet ﷺ used to pray the Duha (forenoon) prayer?" Anas said, "I did not see him praying the Duha prayer except on that day." (Using translation from Bukhārī 670)   

رَجُلٌ مِنَ الْأَنْصَارِ لِلنَّبِيِّ ﷺ إِنِّي لَا أَسْتَطِيعُ الصَّلَاةَ مَعَكَ قَالَ وَكَانَ رَجُلًا ضَخْمًا فَصَنَعَ لِلنَّبِيِّ ﷺ طَعَامًا فَدَعَاهُ إِلَى مَنْزِلِهِ وَبَسَطَ لَهُ حَصِيرًا وَنَضَحَ طَرَفَ الْحَصِيرِ فَصَلَّى عَلَيْهِ رَسُولُ اللهِ ﷺ رَكْعَتَيْنِ فَقَالَ رَجُلٌ مِنْ آلِ الْجَارُودِ وَلِأَنَسِ بْنِ مَالِكٍ أَكَانَ رَسُولُ اللهِ ﷺ يُصَلِّي الضُّحَى؟ فَقَالَ مَا رَأَيْتُهُ صَلَّاهَا إِلَّا يَوْمَئِذٍ