Nasai

English Translation:

Always fasting is against human nature because it would cause deficiencies in the fulfillment of the rights of others (huquq al-‘ibad), lead to physical weakness, disrupt one’s livelihood, and so on. Therefore, perpetual fasting is not correct, even if one were to leave out the fasts of the two Eids and the days of Tashriq, because the aforementioned harms would still be present in exactly the same way in this case as well. Although, from a jurisprudential (fiqhi) perspective, its permissibility has been argued on the basis that, due to the five days of omission, it is not truly perpetual fasting. However, rather than engaging in jurisprudential subtleties, it is essential to consider the benefits (masalih) and harms (mafasid). This principle is clearly observable in the rulings of the Shari‘ah; for example: the leftover water from a dog is impure, while that of a cat is pure; a small quantity of stored water becomes impure with a little impurity, but open water does not, and so on.