It was narrated that ‘Aishah said:
“When the Prophet (peace be upon him) wanted to start I’tikaf, he would pray the Subh, then he would enter the place where he wanted to observe I’tikaf. He wanted to spend the last ten days of Ramadan in I’tikaf, so he ordered that a tent be set up for him.” Then ‘Aishah ordered that a tent be set up for her, and Hafash ordered that a tent be set up for her. When Zainab saw their two tents, she also ordered that a tent be set up for her. When the Messenger of Allah (peace be upon him) saw that, he said: “It is righteousness that you seek?” Then he did not observe I’tikaf during Ramadan, and he observed I’tikaf during ten days of Shawwal.
(Sunan Ibn Majah, Vol. 1, Book 7, Hadith 1843)