What is the most effective way for a believer to purify a utensil that has been licked by a dog, according to the teachings of the Prophet Muhammad (saw)?
 Abu Huraira reported:                      The Messenger of Allah (may peace be upon him) said: The purification of the utensil belonging to any one of you, after it is licked by a dog, lies in washing it seven times, using sand for the first time.