Al-Husayn, from Fadalah, from Sayf, from Abu Bakr, from Abu Abdillah عليه السلام, peace be upon him, who said:
My father asked Imam عليه السلام, while I was listening, about ‘the limit of the illness in which fasting is to be left.’ Imam عليه السلام said: “When he is not able to take the pre-dawn meal.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 406