Is it permissible to sell or buy a dog, and is its price lawful or unlawful? What is the ruling if the purchase is for guarding or hunting purposes?

The general rule is that it is impermissible to sell, buy, or own a dog, and its price is unlawful, due to the Prophet's (peace be upon him) prohibition of the price of a dog. However, some scholars have permitted the sale and purchase of hunting dogs and the like, and considered their price lawful, based on the hadith (definition): "The Messenger of Allah (peace be upon him) prohibited the price of a dog, except for a hunting dog." This latter opinion is the more prevalent one.