Sahih Muslim Book - 15, Hadith - 3324

حَدَّثَنِى زُهَيْرُ بْنُ حَرْبٍ حَدَّثَنَا يَزِيدُ بْنُ هَارُونَ أَخْبَرَنَا عَاصِمٌ الأَحْوَلُ قَالَ سَأَلْتُ أَنَسًا أَحَرَّمَ رَسُولُ اللَّهِ -صلى الله عليه وسلم- الْمَدِينَةَ قَالَ نَعَمْ هِىَ حَرَامٌ لاَ يُخْتَلَى خَلاَهَا فَمَنْ فَعَلَ ذَلِكَ فَعَلَيْهِ لَعْنَةُ اللَّهِ وَالْمَلاَئِكَةِ وَالنَّاسِ أَجْمَعِينَ.

Asim Al-Ahwal said: “I asked Anas ‘Did The Messenger Of Allah (SAW) declare Al-Madinah sacred?’ He said: ’Yes, it is sacred and its grass is not to be cut .Whoever does that, upon him be the curse of Allah, the Angles and all the people.””