كتاب الأيمان
27  
The Book of Oaths
(7)
Chapter: The vow of a disbeliever, and what he should do about it if he becomes a muslim
(7)
باب نَذْرِ الْكَافِرِ وَمَا يَفْعَلُ فِيهِ إِذَا أَسْلَمَ ‏‏
Sahih Muslim 1656 e

Nafi' reported:

A mention of Allah's Messenger (ﷺ) observing 'Umra from ja'rina was made before Ibn 'Umar. He said: He did not enter into the state of Ihram from that (place), and Umar had taken a vow of observing I'tikaf for a night during the days of Ignorance. The rest of the hadith is the same.
وَحَدَّثَنَا أَحْمَدُ بْنُ عَبْدَةَ الضَّبِّيُّ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، حَدَّثَنَا أَيُّوبُ، عَنْ نَافِعٍ، قَالَ ذُكِرَ عِنْدَ ابْنِ عُمَرَ عُمْرَةُ رَسُولِ اللَّهِ صلى الله عليه وسلم مِنَ الْجِعْرَانَةِ فَقَالَ لَمْ يَعْتَمِرْ مِنْهَا - قَالَ - وَكَانَ عُمَرُ نَذَرَ اعْتِكَافَ لَيْلَةٍ فِي الْجَاهِلِيَّةِ ‏.‏ ثُمَّ ذَكَرَ نَحْوَ حَدِيثِ جَرِيرِ بْنِ حَازِمٍ وَمَعْمَرٍ عَنْ أَيُّوبَ ‏.‏
Reference : Sahih Muslim 1656e
In-book reference : Book 27, Hadith 43
USC-MSA web (English) reference : Book 15, Hadith 4076
  (deprecated numbering scheme)