Islam is based on purity in entirety. Allah commands believers to earn sustenance by the lawful job and in the lawful path, and to eat halal things. Allah says in the Quran:

'O people! Eat of what is lawful and good on earth, and do not follow the footsteps of Satan. He is to you an open enemy.' (Surah al-Baqarah verse 168)

In this ayah, Allah urges not only the believers but all people to eat the lawful and good things. Allah gives the general permission for His earthly servants to eat of the halal and good things He has created for them. There is no need to list the halal and good blessings by name. Because there are many.

'He commands you to do evil and vice, and to say about Allah what you do not know.' (Surah al-Baqarah verse 169)

Those who follow in the footsteps of Satan do not prefer to follow the Quran revealed by Allah and the rules of Islam and prefer to follow what their ancestors had left. This is nothing but foolishness. Do they follow anything but the command of Allah? After all, who are their ancestors? Perhaps they are the ones who have gone astray because of their foolishness?

The example of the unbeliever is like the one shouting at an animal that hears only the call. But they are deaf, dumb and blind, so they do not understand.