Sahih Muslim , Book 7, Hadith 3186 (USC-MSA) ⓘ
Abu Huraira (Allah be pleased with him) reported Allah's Messenger as saying: There are at the approaches of Medina angels so that plague and the Dajjal shall not penetrate into it.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نُعَيْمِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " عَلَى أَنْقَابِ الْمَدِينَةِ مَلاَئِكَةٌ لاَ يَدْخُلُهَا الطَّاعُونُ وَلاَ الدَّجَّالُ " .
also referenced under: Book 15, Hadith 554 (In-Book) & Hadith 1379 (Reference)