Is the money taken from selling fertilizers to merchants for more than their official price, in addition to the profit generated from using the car purchased with some of this money, lawful or unlawful? And how does one repent if this money is unlawful?

The employee is entrusted with what is under their hand and is not permitted to act except in a way that serves the interest of the work. If there is a surplus of fertilizers and difficulty in storing them, it is permissible to sell them to non-farmers, and all the money must be paid to the association. Employees are not allowed to take anything from it, as it constitutes a betrayal of public funds.

A severe warning has been issued against taking from public funds, as narrated by Al-Bukhari and Muslim from Abu Hurairah (may Allah be pleased with him) that the Prophet (peace be upon him) mentioned embezzlement and its gravity, saying: "I do not want to see any of you on the Day of Resurrection with a sheep bleating on his neck..." and so on, the Hadith.

There is no harm in using a car purchased with money mixed with unlawful money. The path to repentance is to tally what was taken from the funds and return it to the association, either by selling the car or by operating it and repaying what you owe from its profits. If the bank debt is in installments, then expedite the repayment of the association's money first.

The principle is to return the money to the association. If that is difficult or would cause you harm, then spend it on public welfare projects that the state funds, such as building mosques and schools. This is not charity, but rather a way to rid oneself of unlawful wealth.