حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا اللَّيْثُ، عَنْ عُقَيْلٍ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يَعْتَكِفُ الْعَشْرَ الأَوَاخِرَ مِنْ رَمَضَانَ حَتَّى قَبَضَهُ اللَّهُ ثُمَّ اعْتَكَفَ أَزْوَاجُهُ مِنْ بَعْدِهِ ‏.‏

'Aishah said: The Prophet (PBUH) used to observe retirement (i'tikaf) to the mosque during the last ten days of Ramadan till Allah took him, and then his wives observed retirement to the mosque after his death. Translation Not Available

Book Ref: Sunan Abi Dawud Book 14 Hadith 2462
Web Ref:  Sunan Abi Dawud Book 13 Hadith 2456