Abu Musa Al-Ash`ari, radi Allahu ‘anhu, reported that the
Prophet, sal Allahu alayhi wa sallam, said,
“The example of a good companion and a bad one is the bearer of
musk and the worker on the fires. A bearer of musk would give
you some, you might buy some from him, or you might enjoy the
fragrance of his musk. The worker on the fires, on the other
hand, might spoil your clothes with sparks from his bellows, or
you get a bad smell from him.” Bukhari and Muslim