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. (FR)
English reference (FR): Vol. 1, Book 7, Hadith 1770 (FR)
Arabic reference (FR): Book 7, Hadith 1842 (FR)