From Sahih Bukhari (Hadith 4998):
Narrated Abu-Huraira:Gabriel used to repeat the recitation of the Qur'an with the Prophet (ﷺ) once a year, but he repeated it twice with him in the year he died. The Prophet (ﷺ) used to stay in I`tikaf for ten days every year (in the month of Ramadan), but in the year of his death, he stayed in I`tikaf for twenty days
Reference: Bukhari 4998