It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) declared Madinah Munawwarah as a sanctuary from this place to that place and said: Whoever introduces an innovation here or gives refuge to an innovator, upon him is the curse of Allah, the angels, and all people. The trees here should not be cut.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 13499