Sahih Muslim , Book 7, Hadith 3177 (USC-MSA) ⓘ
Sahl b. Hunif reported that Allah's Messenger pointed with his hands towards Medina and said: That is a sacred territory and a place of safety.
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنِ الشَّيْبَانِيِّ، عَنْ يُسَيْرِ، بْنِ عَمْرٍو عَنْ سَهْلِ بْنِ حُنَيْفٍ، قَالَ أَهْوَى رَسُولُ اللَّهِ صلى الله عليه وسلم بِيَدِهِ إِلَى الْمَدِينَةِ فَقَالَ " إِنَّهَا حَرَمٌ آمِنٌ " .
also referenced under: Book 15, Hadith 545 (In-Book) & Hadith 1375 (Reference)