It was narrated that 'Imran bin Husain said:"I asked the Prophet (ﷺ) about one who prays sitting down. He said: 'Whoever prays standing up is better, and one who prays sitting down will have half the reward of one who prays standing up. And whoever prays lying down will have half the reward of one who prays sitting down

English translation · Sunan an-Nasa'i