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