'Abdullah bin 'Umar (RA) (Allah be pleased with both of them) reported that the Messenger of Allah (ﷺ) used to observe i'tikaf in the last ten days of Ramadan. Nafi' said:'Abdullah (RA) showed me the place in the mosque where the Messenger of Allah (ﷺ) used to observe i'tikaf.
'A'isha (Allah be pleased with her) reported that the Messenger of Allah (ﷺ) (may peace he upon him) used to observe i'tikif in the last ten days of Ramadan till Allah called him back (to his heavenly home). Then his wives observed i'tikaf after him.