How can a person who fell short in his work make amends for his sin?

Is it permissible to work as a butcher in a non-Muslim country where they do not slaughter the meat in the manner prescribed in Islam?

Riba is haram for the one who takes it and the one who pays it, and it is haram to help with it in any way whatsoever

The boss is mistreating an employee and not giving him his due wages; is it permissible for the accountant to restore the employee’s right without the knowledge of the boss so as to redress the wrong that has been done?

Ruling on working with companies that do surveys on the Internet

He works as a nurse, which means that he may do some things that are not acceptable according to sharee‘ah

She is an author who writes stories and articles in English, and is asking about the ruling on writing and receiving payment for it

He works in a company that stores files of various companies, including insurance companies and riba-based banks

Ruling on working in a debt purchasing company

The company gave him some money to buy a computer to develop his skills at work; is it permissible for him to sell it and make use of the money?