The vow of a disbeliever, and what he should do about it if he becomes a muslim
وَحَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ لَمَّا قَفَلَ النَّبِيُّ صلى الله عليه وسلم مِنْ حُنَيْنٍ سَأَلَ عُمَرُ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ نَذْرٍ كَانَ نَذَرَهُ فِي الْجَاهِلِيَّةِ اعْتِكَافِ يَوْمٍ . ثُمَّ ذَكَرَ بِمَعْنَى حَدِيثِ جَرِيرِ بْنِ حَازِمٍ .
lbn 'Umar reported: When Allah's Messenger (ﷺ) came back from the Battle of Hunain, Umar asked Allah's Messenger (ﷺ) about the vow he had taken during the days of Ignorance that he would observe I'tikaf for a day. The rest of the hadith is the same.