Bukhari

Hadith Commentary:
Khabbab ibn al-Aratt radi Allahu anhu is a well-known Companion. His kunyah is Abu Abdullah. In the era of ignorance (Jahiliyyah), the oppressors had imprisoned him. A woman from the Khuza‘ah tribe purchased him and set him free. He had embraced Islam even before the Prophet sallallahu alayhi wa sallam entered the house of Arqam. The disbelievers subjected him to severe hardships, but he remained patient. He settled in Kufa, and there he passed away in the year 37 AH at the age of 73.
From this hadith, Imam al-Bukhari rahimahullah established the permissibility of working as a blacksmith. It is also established from the Noble Qur’an that Dawud alayhis salam used to make excellent weapons from iron.

Hadith Commentary:
(1)
In the hadith, a bad companion is likened to a blacksmith’s furnace.
Apparently, this hadith seems to indicate something objectionable about the profession of a blacksmith.
Imam Bukhari rahimahullah has clarified through the mentioned chapter heading and the presented hadith that this profession existed during the blessed era of the Messenger of Allah sallallahu alayhi wa sallam, and therefore, there is nothing objectionable in adopting this profession. Rather, it is established from the Noble Qur’an that Dawud alayhis salam was also associated with the profession of working with iron, and he used to make excellent weapons from it.
(2)
Imam Bukhari rahimahullah has deduced from the pre-Islamic actions of Khabbab ibn al-Aratt radi Allahu anhu that if this profession were unlawful, then after becoming Muslim, he would not have demanded the obligatory debt from this unlawful work.
The apparent words of the hadith indicate that he requested the wage for his pre-Islamic work.
In fact, Khabbab radi Allahu anhu continued to practice this profession even after embracing Islam, as Imam Bukhari rahimahullah has established in the Book of Hiring (Kitab al-Ijarah).
(Sahih al-Bukhari, al-Ijarah, Hadith: 2275)