Some of my colleagues are continuously involved in wrongdoings at the office; they overcharge clients, manipulate invoices, etc. I tried to make them stop doing that several times, but nothing has changed. Is it appropriate to inform the owners about this, or should I hide this as they are my Muslim brothers? I am sure that if I informed the superior, they will lose their job and their families will also suffer along with them. Kindly advise.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger. 

We ask Allah, The Exalted, to bless you with guidance and make you keener on adhering to the truth. What you did of trying to stop your colleagues is what is required of the Muslim, in compliance with the command of the Prophet, sallallahu ‘alayhi wa sallam, “Whoever among you sees an evil, then he should change it with his hand. If he cannot do that, then with his tongue. If he cannot do that, then with his heart, and that is the weakest form of faith.” [Muslim] Moreover, he, sallallahu ‘alayhi wa sallam, said, “The religion is (based on the exchange of sincere) advice.” The people asked, “To whom?” He said, “To Allah, to His Book, to His Messenger, to the leaders of the Muslims, and to the common folk.” [Muslim]

As for reporting the actions of these employees to their superiors, you should know that if these employees do not refrain from what they are doing and are not deterred (by your advice), it is permissible for you – or perhaps even obligatory on you – to inform the superiors of their actions in order to put an end to the harm that they are causing. Bareeqah Madmoodiyyah  reads about backbiting, “Nameemah (slander) often refers to the act of conveying the information of a bad conversation from one person to another, and it is prohibited unless the reported information about that person wards off harm from the one to whom the information is conveyed, who is unaware of it, and the harm cannot be repelled except by informing him. In this case, it is obligatory to inform the concerned person of this information because it is considered exchange of sincere advice among Muslims.”

First, threaten those employees that you will report their violations to their superiors. If they do not stop, then report them to the superiors out of sincere advice and to ward off harm from the superiors and from the clients whom they wrong and whose money they usurp unlawfully.

Allah knows best.