Ahmad ibn Muhammad from Ali ibn Ahmad ibn Ashyam from Muhammad ibn Ibrahim Al-Hudayni, who said:
I asked Imam عليه السلام about a man who prays upon a bed while he is able to pray on the ground. So Imam عليه السلام wrote: "There is no harm; pray upon it."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 335