I say, and with God's help: It is forbidden for one who is in a mandatory I'tikaf to leave their place of I'tikaf, even if it is in the mosque of the house for a woman, except for the following: First: A legitimate need: such as Friday, and their exit for Friday should be at the time of noon. As for someone who is far from the mosque, they should leave at a time that allows them to catch the Friday prayer with its Sunnah prayers before it, which are four. Their I'tikaf is not invalidated by staying longer than the Sunnah prayers in the mosque, or if they complete their I'tikaf in the mosque, and it is disliked as a matter of etiquette. Likewise, if they leave for the call to prayer, even if they are not the caller, and if the minaret is outside the mosque; for Aisha (may Allah be pleased with her) said: 'I would enter the house for a need and for the sick therein, and I would not ask about it except while passing by. And the Messenger of Allah (peace be upon him) would enter to me with his head while he was in the mosque, his feet were not inside. He would not enter the house except for a need when he was in I'tikaf.' In Sahih Muslim 1: 244, and Sahih Bukhari 2: 714. This is because these matters are known to occur during the time of I'tikaf, so they are exempted out of necessity, and Friday is one of their most important needs, thus it is permissible for them to leave for it; because they are commanded to strive towards it by His saying, exalted is He: {So strive toward the remembrance of Allah} (Al-Jumu'ah: 9), so leaving for it is considered an exception: like a person's need. Second: A natural need: such as urination and defecation, and washing if one has a wet dream and cannot wash in the mosque, but they should not linger after completing their purification. Third: A necessary need: such as the collapse of the mosque, expelling an oppressor by force, fear for oneself, or one’s belongings from aggressors. In these cases, they may enter another mosque to complete their I'tikaf. See: Al-'Alaiyah p. 184, Al-Taybin 1: 351, Al-Hadiyah Al-'Alaiyah p. 184, Sharh Al-Wiqayah for Sadr Al-Shari'ah p. 245, Majma' Al-Anhar 1: 256, and Al-Mabsut 3: 117, and Allah knows best.