Sahih Bukhari Volume 7, Book 67, Hadith Number 442.

Narrated By Abu Musa : The Prophet said, ‘The example of a good pious companion and an evil one is that of a person carrying musk and another blowing a pair of bellows. The one who is carrying musk will either give you some perfume as a present, or you will buy some from him, or you will get a good smell from him, but the one who is blowing a pair of bellows will either burn your clothes or you will get a bad smell from him.”