Sahih Muslim Book 7, Hadith Number 3155.

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.

‘Amir b. Sa’d b. Abu Waqqas reported on the authority of his father (Allah be pleased with him) that Allah’s Messenger (may peace be upon him) said, and then the (above-mentioned) Hadith was narrated with this addition: “None should nurse ill-will towards the people of Medina, or Allah will melt him in fire like the melting of lead or the dissolution of salt in water.