Sahih Bukhari: Hadith 1973

Allah's Messenger (ﷺ) used to practice I`tikaf every year in the month of Ramadan. And after offering the morning prayer, he used to enter the place of his I`tikaf. `Aisha asked his permission to let her practice I`tikaf and he allowed her, and so she pitched a tent in the mosque. When Hafsa heard of that, she also pitched a tent (for herself), and when Zainab heard of that, she too pitched another tent. When, in the morning, Allah's Messenger (ﷺ) had finished the morning prayer, he saw four tents and asked, "What is this?" He was informed about it. He then said, "What made them do this? Is it righteousness? Remove the tents, for I do not want to see them." So, the tents were removed. The Prophet (ﷺ) did not perform I`tikaf that year in the month of Ramadan, but did it in the last ten days of Shawwal.