Yahya related to me from Malik from Nuaym ibn Abdullah al-Mujmirthat Abu Hurayra said, "The Messenger of Allah, may Allah bless himand grant him peace, said, 'There are angels at the entries of Madina,and neither plague nor the Dajjal will enter it.' "
USC-MSA web (English) reference: Book 45, Hadith 16
Arabic reference: Book 45, Hadith 1616