It wasnarrated from 'Imran bin Husain that he asked the Messenger ofAllah (ﷺ) about a man who prays sitting down. He said, "Whoeverperforms prayer standing up, that is better. Whoever performs prayersitting down will have half the reward of one who prays standing. Andwhoever performs prayer lying down will have half the reward of onewho prays sitting."
English reference: Vol. 1, Book 5, Hadith 1231
Arabic reference: Book 5, Hadith 1289