It wasnarrated from Ubayy bin Ka'b that:
The Prophet (ﷺ) used tospendthe last ten days of Ramadan in I'tikaf. One year he wastraveling,so the following year he spent twenty days in I'tikaf. (IT)
English reference (IT): Vol. 1, Book 7, Hadith 1770 (IT)
Arabic reference (IT): Book 7, Hadith 1842 (IT)