Mark 1

After having healed a leper that Lord asked him -

"...See thou say nothing to any man: but go thy way, shew thyself to the priest, and offer for thy cleansing those things which Moses commanded, for a testimony unto them."  (Mark 1:44)

It appears to me that the purpose the Savior did not want this to spread was because He wanted to continue to preach and teach in the cities and synagogues.  But the healed leper -

"...began to publish it much, and to blaze abroad the matter, insomuch that Jesus could no more openly enter into the city, but was without in desert places: and they came to him from every quarter."
(Mark 1:45)

In my mind, this is why many of His sermons are on the "mount" or desert land.