(1) باب الاِعْتِكَافِ فِي الْعَشْرِ الأَوَاخِرِ وَالاِعْتِكَافِ فِي الْمَسَاجِدِ كُلِّهَا
Narrated `Abdullah bin `Umar:
Allah's Messenger (ﷺ) used to practice I`tikaf in the last ten days of the month of Ramadan.
Reference: Sahih al-Bukhari 2025
In-book reference: Book 33, Hadith 1
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 33, Hadith 242