Sahih Muslim Book 7, Hadith Number 3161.

Chapter : Eminence of Medina, Allah’s Apostle (may peace be upon him) showered blessings upon it. Its sacredness and unlawfulness of hunting and lopping of trees and demarcation its precincts.

Anas b. Malik (Allah be pleased with him) reported that Allah’s Messenger (may peace be upon him) said: Allah bless them in their measurements, bless them in their sa’s and bless them in their mudd.