Sahih al-Bukhari 2045
Retiring to a Mosque for Remembrance of Allah (I'tikaf)
Whoever intended I'tikaf and then changed his mind
Narrated `Amra bint `Abdur-Rahman from `Aisha: Allah's Messenger (ﷺ) mentioned that he would practice I`tikaf in the last ten days of Ramadan. `Aisha asked his permission to perform I`tikaf and he permitted her. Hafsa asked `Aisha to take his permission for her, and she did so. When Zainab bint Jahsh saw that, she ordered a tent to be pitched for her and it was pitched for her. Allah's Messenger (ﷺ) used to proceed to his tent after the prayer. So, he saw the tents ans asked, "What is this?" He was told that those were the tents of Aisha, Hafsa, and Zainab. Allah's Messenger (ﷺ) said, "Is it righteousness which they intended by doing so? I am not going to perform I`tikaf." So he returned home. When the fasting month was over, he performed Itikar for ten days in the month of Shawwal.