NASAI-KUBRA 3329: from Abū Hurayrah —
[Machine] The passage translates to: "It is narrated from the Prophet ﷺ that he used to observe itikaf during the last ten days of Ramadan. However, in the year he passed away, he observed itikaf for twenty days."

الكبرى للنسائي ٣٣٢٩: عن ابو هريره —
عَنِ النَّبِيِّ ﷺ أَنَّهُ كَانَ «يَعْتَكِفُ الْعَشْرَ الْأَوَاخِرَ مِنْ شَهْرِ رَمَضَانَ فَلَمَّا كَانَ الْعَامُ الَّذِي قُبِضَ فِيهِ اعْتَكَفَ عِشْرِينَ»


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Nasāʾī's Kubrá > Retiring to a Mosque > § [Machine] I'tikaf in the middle ten days of the month
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