Aisha (may Allah be pleased with her) said: The Sunnah for the one observing I'tikaf is that he should not exit except for what is indispensable for him. It was recorded by Abu Dawud (1). She also said: The Messenger of Allah (may Allah bless him and grant him peace), when he observed I'tikaf, would lean his head towards me and I would comb his hair, and he would not enter the house except for human necessity. Agreed upon (2). There is no disagreement that he may exit for what is indispensable for him. Ibn al-Mundhir (3) said: The scholars have reached a consensus that the one observing I'tikaf may exit his place of I'tikaf for defecation and urination. This is because this is among the indispensable necessities, and it is impossible to perform it inside the mosque. If I'tikaf were to be invalidated by exiting for this, no one's I'tikaf would be valid. Furthermore, the Prophet (may Allah bless him and grant him peace) used to observe I'tikaf, and we know that he used to exit to relieve himself. The intent by "human necessity" is urination and defecation; these were alluded to by this expression because every human needs to perform them. Included in this meaning is the need for food and drink if he does not have someone to bring them to him; he may exit for that if he is in need. If he is overcome by vomiting, he may exit to vomit outside the mosque. For everything that is indispensable and cannot be performed inside the mosque, he may exit for it, and his I'tikaf is not invalidated while he is doing it, provided he does not prolong it. Similarly, he may exit for what Allah the Almighty has obligated upon him, such as one who observes I'tikaf in a mosque where the Friday prayer is not held; he needs to exit to perform the Friday prayer, and it is incumbent upon him to proceed to it, so he may exit for it and his I'tikaf is not invalidated. Abu Hanifah stated this. Al-Shafi'i said: One should not observe I'tikaf in other than a congregational mosque if his I'tikaf is interrupted by a Friday prayer. If he makes a vow for consecutive I'tikaf and exits for the Friday prayer, his I'tikaf is invalidated, and he must restart; because it was possible for him to perform his obligatory act in a place from which he would not have to exit, so it was invalidated by exiting, similar to one who is performing kaffarah (expiation) and begins the two consecutive months of fasting in Sha'ban or Dhu al-Hijjah. Our argument is that he exited for an obligatory act, so his I'tikaf is not invalidated, just like a woman in the waiting period ('iddah) who exits to fulfill the requirements of the 'iddah, or one who exits to save a drowning person, extinguish a fire, or perform testimony that has become individually incumbent upon him.