From him, from Ahmad ibn Muhammad, from Muhammad ibn Sahl, from his father, who said:
I asked Abu al-Hasan عليه السلام, peace be upon him, about a man who performs the supererogatory prayer (al-nafilah) sitting down, and he has no illness, whether in travel or at home. Imam عليه السلام said: “There is no harm.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 3, p. 254
