وَعَنْ عُمَرَ رضى الله عنه
قَالَ: «قُلْتُ: يَا رَسُولَ اَللَّهِ! إِنِّي نَذَرْتُ فِي اَلْجَاهِلِيَّةِ; أَنْ أَعْتَكِفَ لَيْلَةً فِي اَلْمَسْجِدِ اَلْحَرَامِ. قَالَ: «فَأَوْفِ بِنَذْرِكَ»
He said: I said: O Messenger of Allah (sallallahu alayhi wa sallam), I made a vow in the Jahiliyya times to spend a night in devotion (Itikaf) in the Sacred Mosque. He (the Prophet (sallallahu alayhi wa sallam)) said: “Fulfill your vow.”. al-Bukhari added in another narration: “Then, spend a night in devotion (in the Sacred Mosque).”
Bulugh al-Maram 1578, Book 13, Oaths and Vows, Hadith 23. 1 min read