The World Federation One Stop Fiqh

Ruling 2673

If a person vows to refrain from an act but does not specify a period for it, in the event that he does the act owing to forgetfulness, necessity, negligence, error, or because someone compelled him, or he was inculpably ignorant (al‐jāhil al‐qāṣir),5 then in any of these cases, it is not obligatory for him to give kaffārah. However, the vow remains in place; therefore, if he does the act volitionally from then onwards, he must give kaffārah.

5 ‘Inculpably ignorant’ is a term used to refer to someone who has a valid excuse for not knowing; for example, he relied upon something that he thought was authoritative but in fact was not.