Sahih Bukhari | Volume 9 | Hadith Number 110

Narrated by 'Amr bin Ash-Sharid
Abu Rafi' sold a house to Sa'd bin Malik for four-hundred Mithqal of gold, and said, "If I had not heard the Prophet saying, 'The neighbour has more right to be taken care of by his neighbour (than anyone else),' then I would not have sold it to you."