Retiring to a Mosque for Remembrance of Allah (I'tikaf)

Bukhari :: Book 3 :: Volume 33 :: Hadith 242

Narrated Abdullah bin Umar:

Allah's Apostle used to practise Itikaf in the last ten days of the month of Ramadan.

Source materials are from the University of Southern California MSA site
Hadith eBooks converted from Imaan Star