It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that he asked the Messenger of Allah (peace and blessings be upon him) about a man praying sitting, and he (peace and blessings be upon him) said: "His praying standing is better; his prayer sitting is equal to half of his prayer standing, and his prayer lying down is equal to half of his prayer sitting."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15683