How does one purify themself and their wealth if their lawful earnings became mixed with unlawful gains due to a past job, where the employee overcharged customers and took merchandise for personal use without the employer's knowledge?

The question addresses the ruling on increasing the price beyond what the employer has set, the ruling on taking money from the employer without their consent, and the ruling on taking more than the amount of the injustice suffered.

Firstly: The ruling on increasing the price: It is not permissible for an agent to increase the price beyond what the employer has set for them; any increase obtained belongs to the principal, not the agent.

Secondly: The ruling on taking money from the employer without their consent (the issue of "al-zafar" or obtaining one's right): The fundamental principle is prohibition. However, if the employer is an oppressor, jurists have differed on the permissibility for the wronged party to take their right without the oppressor's consent: Hanafi school: It is permissible for the debtor to take their right from the same type of money and in the same form. Maliki school: It is not permissible for a depositor to take their debt from a deposit placed with the oppressor. Shafi'i school: It is permissible to take from the same type of right or from a different type, provided that the judge is not aware of the situation, the wronged party cannot provide evidence, and they do not sell to themselves. Hanbali school: It is forbidden to take one's right if it cannot be obtained through a judge, even if the oppressor has assets.

The religious fatwa permits this to the extent of the injustice suffered, with the obligation to be precise and accurate, based on the Almighty's saying: ﴿AND THEY SEEK ASSISTANCE AFTER THEY HAVE BEEN WRONGED﴾ [Ash-Shu'ara: 227], the Hadith of Hind bint Utbah: "TAKE WHAT IS SUFFICIENT FOR YOU AND YOUR CHILDREN IN A REASONABLE MANNER," and the Hadith of Uqbah ibn Amir regarding the right of a guest: "SO TAKE FROM THEM THE RIGHT OF A GUEST THAT IS DUE TO THEM."

Thirdly: If the taking exceeds the amount of injustice suffered: This is considered treachery and is forbidden by Islamic law, based on the Almighty's saying: ﴿INDEED, ALLAH DOES NOT LIKE THE TREACHEROUS﴾ [Al-Anfal: 58], and the Prophet's (peace be upon him) saying: "RETURN THE TRUST TO THE ONE WHO ENTRUSTED YOU, AND DO NOT BETRAY THE ONE WHO BETRAYED YOU." Repentance is obligatory, and the excess amount must be returned to its owners through appropriate means. Giving it as charity on their behalf is not sufficient unless returning it becomes impossible after making every effort to find them or their heirs.