حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، حَدَّثَنَا يَحْيَى، عَنْ عُبَيْدِ اللَّهِ، حَدَّثَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ، عَنْ عُمَرَ، رَضِيَ اللَّهُ عَنْهُ أَنَّهُ قَالَ : يَا رَسُولَ اللَّهِ إِنِّي نَذَرْتُ فِي الْجَاهِلِيَّةِ أَنْ أَعْتَكِفَ فِي الْمَسْجِدِ الْحَرَامِ لَيْلَةً . فَقَالَ لَهُ النَّبِيُّ صلى الله عليه وسلم : " أَوْفِ بِنَذْرِكَ " .
Narrated Ibn 'Umar: That 'Umar said: Messenger of Allah, I took a vow in pre-Islamic times that I would stay in the sacred mosque (Masjid Haram) as a devotion (i'tikaf). The Prophet (PBUH) said: Fulfill your vow. Translation Not Available
Book Ref: Sunan Abi Dawud Book 22 Hadith 3325
Web Ref: Sunan Abi Dawud Book 21 Hadith 3319