Sahih al-Bukhari — Retiring to a Mosque for Remembrance of Allah (I'tikaf) — Hadith No: 2034
Translation
Narrated `Aisha:The Prophet (ﷺ) intended to practice I`tikaf and when he reached the place where he intended to perform I`tikaf, he saw some tents, the tents of `Aisha, Hafsa and Zainab. So, he said, "Do you consider that they intended to do righteousness by doing this?" And then he went away and did not perform I`tikaf (in Ramadan) but performed it in the month of Shawwal for ten days