Bulugh al-Maram, Book 5, Hadith 719 (English) ⓘ
'A’isha (RAA) narrated, ’The Messenger of Allah used to perform I'tikaf during the last ten days of Ramadan until he died. Then his wives used to perform I'tikaf after his death.’ Agreed upon.
وَعَنْهَا: { أَنَّ اَلنَّبِيَّ - صلى الله عليه وسلم -كَانَ يَعْتَكِفُ اَلْعَشْرَ اَلْأَوَاخِرَ مِنْ رَمَضَانَ, حَتَّى تَوَفَّاهُ اَللَّهُ, ثُمَّ اعْتَكَفَ أَزْوَاجُهُ مِنْ بَعْدِهِ } مُتَّفَقٌ عَلَيْهِ 1. 1 - صحيح. رواه البخاري ( 2025 )، ومسلم ( 1172 ) ( 5 ).
also referenced under: Book 5, Hadith 699 (In-Book)