Maliks Muwatta Book 15, Hadith Number 13.

Yahya related to me from Malik from Nafi, the mawla of Ibn Umar that a man from Egypt told him that Umar ibn al-Khattab recited Surat al-Hajj (Sura 22) and prostrated twice in it, and then said, “This sura has been given special preference by having two prostrations in it.”