Muwatta Imam Malik (Riwayat Yahya)

Imam Malik, may Allah have mercy on him, said: What I have heard from the people of knowledge is that when a sick person is afflicted with such an illness that fasting becomes hard for him, and fasting causes him hardship, and the illness reaches such a degree, then it is permissible for him to break the fast. Similarly, when it becomes difficult for a sick person to stand in prayer, and the illness reaches such a degree that it is considered an excuse in the sight of Allah, Glorious and Exalted is He, and Allah knows better about the servant than the servant himself, and among these illnesses are some that do not reach this degree. In any case, when the illness reaches this degree, then he should pray sitting, because the religion of Allah, the Exalted, is easy, and Allah, Glorious and Exalted is He, has given the traveler a concession not to fast, even though he is more able to fast than the sick person. Allah, Glorious and Exalted is He, said in His Holy Book: "Whoever among you is sick or on a journey, then he should fast the same number of other days." Thus, Allah, Glorious and Exalted is He, has given the traveler a concession to break the fast, even though he is more able to fast than the sick person. And this is most pleasing to me among the statements I have heard in this chapter, and in our view, this matter is agreed upon and there is consensus on it.