Messenger of Allah ﷺ said, "The example of a good companion (who sits with you) in comparison with a bad one, is like that of the musk seller and the blacksmith's bellows (or furnace); from the first you would either buy musk or enjoy its good smell while the bellows would either burn your clothes or your house, or you get a bad nasty smell thereof."  

قَالَ رَسُولُ اللَّهِ ﷺ مَثَلُ الْجَلِيسِ الصَّالِحِ وَالْجَلِيسِ السَّوْءِ كَمَثَلِ صَاحِبِ الْمِسْكِ وَكِيرِ الْحَدَّادِ لاَ يَعْدَمُكَ مِنْ صَاحِبِ الْمِسْكِ إِمَّا تَشْتَرِيهِ أَوْ تَجِدُ رِيحَهُ وَكِيرُ الْحَدَّادِ يُحْرِقُ بَدَنَكَ أَوْ ثَوْبَكَ أَوْ تَجِدُ مِنْهُ رِيحًا خَبِيثَةً