Good and bad companions

It is related that Abu Musa reported that the Messenger of Allah, may Allah bless him and grant him peace, said, "The metaphor of a good companion and a bad companion is that of someone possessing musk and the bellows of the blacksmith. From someone possessing musk you either buy it or smell its scent while the bellows of the blacksmith either burn your body or your clothes or you smell a foul odour from them."