Ibn Abdūs understood it. There are two opinions concerning someone who breaks his fast forgetfully during it. The first is that he need not make it up; this is Sahnūn’s position. The second is that he must make it up while maintaining continuity; this is Ibn al-Qāsim’s position.

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The second kind is a vow to observe iʿtikāf for a number of unspecified days. Someone who makes such a vow may not fulfil it during Ramadan or while observing another obligatory fast, because the vow itself makes fasting obligatory upon him. He may not discharge this obligation by observing iʿtikāf during days on which he is already obliged to fast. This differs from the opinion of Muhammad ibn Abd al-Hakam, reported by Ibn Hārith, that he may fulfil his vow of iʿtikāf during days on which he has vowed to fast.

Once he begins this iʿtikāf, he must complete it and make up any days during which he was ill or broke his fast forgetfully, joining them directly to his iʿtikāf. There is no disagreement on this. If, however, he deliberately breaks his fast, he invalidates his iʿtikāf and must make it up, since beginning it made it binding upon him. He must also undertake another period of iʿtikāf to fulfil his vow. The same difference of opinion applies here as in the case of someone who deliberately breaks his fast while making up a day of Ramadan.

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If someone intends to observe iʿtikāf and begins it without having vowed to do so, it becomes binding upon him by his beginning it, just as a vow to observe it on specified days is binding. The rulings concerning illness during it, or breaking the fast forgetfully or deliberately, must therefore be the same as those already explained for that case. The exception is the third opinion concerning illness, which cannot apply here, since the circumstances it addresses cannot arise in this case. Success comes through Allah alone.