'Asim reported:I asked Anas (Allah be pleased with him) whether Allah's Messenger (ﷺ) had declared Medina as sacred. He said: Yes, it is sacred, so its tree is not to be cut; and he who did that let the curse of Allah and that of the angels and of all people be upon him.
حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا يَزِيدُ بْنُ هَارُونَ، أَخْبَرَنَا عَاصِمٌ الأَحْوَلُ، قَالَ سَأَلْتُ أَنَسًا أَحَرَّمَ رَسُولُ اللَّهِ صلى الله عليه وسلم الْمَدِينَةَ قَالَ نَعَمْ هِيَ حَرَامٌ لاَ يُخْتَلَى خَلاَهَا فَمَنْ فَعَلَ ذَلِكَ فَعَلَيْهِ لَعْنَةُ اللَّهِ وَالْمَلاَئِكَةِ وَالنَّاسِ أَجْمَعِينَ .
Muslim
The Book of Pilgrimage • Hadith 528