It wasnarrated from 'Abdullah bin 'Umar that:
The Messenger of Allah(ﷺ) used to spend the last ten days of Ramadan in I'tikaf. (JA)
English reference (JA): Vol. 1, Book 7, Hadith 1773 (JA)
Arabic reference (JA): Book 7, Hadith 1845 (JA)