'Aishah (May Allah be pleased with her) reported:
The Prophet (ﷺ) used to engage himself in I'tikaf (seclusion for prayers) in the mosque during the last ten nights of Ramadan till he passed away; thereafter, his wives followed this practice after him.[Al- Bukhari and Muslim].
App reference: Book 10, Hadith 2
Arabic/English book reference: Book 10, Hadith 1269