It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) was asked about praying while sitting, and he (peace and blessings be upon him) said: "Praying standing is more virtuous; one who prays sitting receives half the reward of one who prays standing, and one who prays lying down receives half the reward of one who prays sitting."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3680
Anas bin Sirin (may Allah have mercy on him) relates: I heard Sayyiduna Anas bin Malik (may Allah be pleased with him) say: A man of the Ansar said to the Prophet (peace and blessings be upon him): I am not able to pray standing with you (in congregation). He was a heavy-bodied man. He prepared food for the Prophet (peace and blessings be upon him), invited him to his house, spread out a mat for him and cleaned the edge of the mat. The Messenger of Allah (peace and blessings be upon him) prayed two rak'ahs on it. A man from the family of al-Jarud said to Sayyiduna Anas bin Malik (may Allah be pleased with him): Did the Messenger of Allah (peace and blessings be upon him) pray the forenoon (Duha) prayer? He said: I never saw him (peace and blessings be upon him) pray it except on that day.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3681