It has been narrated to me that the Messenger of Allah (ﷺ) said : The Prayer of a man in sitting condition is half the prayer (wins him half the reward of prayer). I came to him and found him prayer in sitting condition. I placed my hand on my head (in surprise). He said: what is the matter,’Abd Allah b. ‘Amr? I said; Messenger of Allah (ﷺ) you have been reported to me as saying : the prayer of a man in sitting condition is half the prayer , but you are praying in sitting condition. He said: yes, but I am not like one of you.
Sunan Abi Dawud Book 2, Hadith 561