Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Musa (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The example of a good companion and a bad companion is like that of the one who carries musk and the one who blows the bellows. The musk carrier will either give you some musk as a gift, or you will buy it from him, and if neither of these two things happens, at least you will get a good fragrance from him. (As for) the one who blows the bellows, either he will burn your clothes, or you will get a bad smell from him."