نَذْرٌ فِي اعْتِكَافِ لَيْلَةٍ فِي الْمَسْجِدِ الْحَرَامِ فَسَأَلَ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ ذَلِكَ فَأَمَرَهُ أَنْ يَعْتَكِفَ
It was narrated that Ibn 'Umar said: "Umar had made a vow to spend a night in 'Itikaf in Al-Masjid Al-Haram. He asked the Messenger of Allah about that, and he ordered him to perform the 'Itikaf."