The ruling concerning neglecting to fast
Question: What is the ruling regarding a Muslim who neglected to fast without a permissible excuse for a number of years? He was fulfilling the other obligations upon him. Does he make them up or seek to expiate them? How would he make these months up if he had to?
Response: The ruling regarding a person who neglected to fast in Ramadhaan whilst he was eligible for that, whether male or female, is that he has disobeyed Allaah and His Messenger and has fallen into a major sin. It is upon him to repent to Allaah due to this, as well as having to make up all that he missed. He must also feed a poor person for each day he missed if he is able to do so. If he is a poor person and cannot feed them, then it is enough for him to make up the days along with repentance. This is because fasting in Ramadhaan is a great obligation. Allaah ordained it upon the Muslims and the Messenger (sal-Allaahu `alayhe wa sallam) has mentioned that it is one of the five pillars of Islaam. If he denies the obligation of fasting Ramadhaan then he is, by that, a disbeliever, belying Allaah and His Messenger. He must be asked to repent from the one in authority through the Islaamic courts. If he does not repent it is obligatory to kill him due to his apostasy, and due to the saying of the Messenger (sal-Allaahu `alayhe wa sallam) that "…whoever changes his religion (from Islaam) then kill him." Reported by Bukhaaree. However, if he did not fast due to illness or travel there is no sin upon him. It is obligatory upon him to make up these fasts once he has recovered from his illness or returned from his travel due to Allaah's saying in the Qur.aan: "and he who was ill or on a journey the prescribed period should be made up by days later". [Soorah al-Baqarah, Aayah 185].
Shaykh Ibn Baaz
Fataawa Ramadhaan - Volume 1, Page 50, Fatwa No.17