Ibn Abi Umayr, from Rifaa, from Abu Abdillah عليه السلام, peace be upon him, who said:
I (narrator) asked Imam عليه السلام about ‘one who is unconscious for a month, what does he make up of the prayer?’ Imam عليه السلام said: “He makes all of it up. Indeed, the matter of prayer is severe.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 314