(15) باب مَنْ لَمْ يَرَ عَلَيْهِ صَوْمًا إِذَا اعْتَكَفَ
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
In-book reference: Book 33, Hadith 17
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 33, Hadith 258