(7) باب نَذْرِ الْكَافِرِ وَمَا يَفْعَلُ فِيهِ إِذَا أَسْلَمَ
Ibn 'Umar reported that Umar (b. Khattab) said:
Messenger of Allah, I had taken a vow during the days of Ignorance (Jahiliyya) that I would observe I'tikaf for a night in the Sacred Mosque. He (the Holy Prophet) said: Fulfil your vow. (IT)
Reference (IT): Sahih Muslim 1656 a (IT)
In-book reference (IT): Book 27, Hadith 40 (IT)
USC-MSA web (English) reference(deprecated numbering scheme): Book 15, Hadith 4072 (IT)