(36) باب إِذَا نَذَرَ ثُمَّ أَسْلَمَ قَبْلَ أَنْ يَفِيَ
It was narrated from Ibn 'Umar, that 'Umar had vowed to spend a night in 'Itikaf during the Jahiliyyah. He asked the Messenger of Allah about that, and he ordered him to perform the 'Itikaf. (ES)
Reference (ES): Sunan an-Nasa'i 3820 (ES)
In-book reference (ES): Book 35, Hadith 60 (ES)
English translation (ES): Vol. 4, Book 35, Hadith 3851 (ES)