When is an oath concerning a specific, divisible act (like praying or fasting) considered broken?
General Chapter
Al-Mughni
Book of Expiations
Primary text
If one swears, 'By Allah, I will not pray a prayer (Salat)' or 'I will not eat a bite (Akla),' the oath is not broken until the entire prayer or the entire bite is completed. If one swears, 'If you experience one menstrual period (Hayda), you are divorced,' she is not divorced until she completes that flow and becomes purified from a subsequent one. If one swears regarding two wives, 'If you both menstruate, you are divorced,' neither is divorced until both have completed menstruation. This demonstrates that the intention relates to completing the whole action.
Supporting text
Ahmad stated that if a man swears to his wife, 'If you fast for a day, you are divorced,' she is divorced upon sunset of that day. Al-Qadi stated that if one swears 'I will not pray a prayer,' the oath is broken upon completing the prostration (Sujud). If one swears not to pray or fast, the oath concerning prayer is broken by the opening Takbir (Takbirat al-Ihram), and for fasting, by the rising of the dawn, if the intention for fasting was present. Al-Shafi'i agrees on the prayer part with the Takbir. Abu Hanifa agrees on fasting but requires a prostration for prayer.