Sahih al-Bukhari 2042
Book 33: Retiring to a Mosque for Remembrance of Allah (I'tikaf) · Narrated by `Abdullah bin `Umar
Arabic
حَدَّثَنَا إِسْمَاعِيلُ بْنُ عَبْدِ اللَّهِ، عَنْ أَخِيهِ، عَنْ سُلَيْمَانَ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنْ عُمَرَ بْنِ الْخَطَّابِ ـ رضى الله عنه ـ أَنَّهُ قَالَ يَا رَسُولَ اللَّهِ إِنِّي نَذَرْتُ فِي الْجَاهِلِيَّةِ أَنْ أَعْتَكِفَ لَيْلَةً فِي الْمَسْجِدِ الْحَرَامِ. فَقَالَ لَهُ النَّبِيُّ صلى الله عليه وسلم " أَوْفِ نَذْرَكَ ". فَاعْتَكَفَ لَيْلَةً.
English translation
Narrated `Abdullah bin `Umar:`Umar bin Al-Khattab said, "O Allah's Messenger (ﷺ)! I vowed in the Pre-Islamic period to perform I`tikaf in Al-Masjid-al-Haram for one night." The Prophet (ﷺ) said, "Fulfill your vow." So, he performed I`tikaf for one night
Reference: Sahih al-Bukhari 2042, Book of Retiring to a Mosque for Remembrance of Allah (I'tikaf). English translation by Dr. Muhammad Muhsin Khan.