Sahih Al Bukhari Hadith Number 1880

Narrated Abu Huraira: Allah’s Messenger (peace be upon him) said, “There are angels guarding the entrances (or roads) of Medina, neither plague nor Ad-Dajjal will be able to enter it.”

29  Virtues of Madinah
Hadith number 1880
Volume no 3
Chapter: 9 (Ad-Dajjal will not be able to enter Al-Madina)