What is the ruling on money acquired by an engineer from his partnership with a contractor, by exploiting his official authority, and how should he deal with the commingled funds whose amount he cannot determine after his repentance and regret?

It is forbidden for an employee to be a secret partner of a contractor. The profits resulting from this partnership are detailed as follows:

1. Profits from work unrelated to the company: Permissible. 2. Profits from work related to the company: If the employee was unaware of the prohibition: It is permissible for him to keep them, based on the Almighty’s saying: ﴿So whoever receives an admonition from his Lord and desists, he may have what has already passed.﴾ If he was aware of the prohibition: He must dispose of them by giving them to the poor and needy or spending them on general Muslim welfare. If he is unaware of the exact amount of these profits, he should donate what he believes is most likely to clear his conscience, and it is preferable to give out half of the mixed funds.