What are the permissible reasons for a person observing i'tikaf to exit the mosque?
General Chapter
Al-Mughni
Book of I'tikaf
Primary text
The established practice for one in i'tikaf is that he must not leave except for what is absolutely necessary. This necessity includes relief of natural needs (urine and feces). There is consensus among scholars that leaving for bodily waste is permissible, as it is an unavoidable necessity that cannot be fulfilled inside the mosque. Necessity also includes needing food and drink if no one brings it, and vomiting. Any essential need that cannot be met inside the mosque permits leaving without invalidating the i'tikaf, provided the departure is not prolonged.
Supporting text
Leaving is also permitted for fulfilling obligations imposed by God, such as leaving for the obligatory Jumu'ah prayer if one is observing i'tikaf in a mosque without it. Al-Shafi'i states that if the i'tikaf encompasses Jumu'ah, one must not observe it in a non-Jumu'ah mosque; and if one vows continuous i'tikaf and leaves for Jumu'ah, the i'tikaf is invalidated, requiring recommencement, as the person could have chosen a mosque where Jumu'ah is held.