What is the ruling on the salary of an employee who spies on his colleagues and reports their news to the manager?

It is not permissible for a Muslim to spy on or track the missteps of his brother and spread them, based on the Almighty's saying: "And do not spy" [49:12] and the Prophet's (peace be upon him) saying: "O community of those who have submitted with their tongues but in whose hearts faith has not yet entered: Do not harm Muslims, nor shame them, nor seek out their faults. For verily, whoever seeks out the fault of his Muslim brother, Allah will seek out his fault."

A distinction is made between prohibited spying and what is not. For example, when a responsible authority appoints employees to monitor the performance of workers and regulate work, or if an employee sees a defect and advises, but is not heeded, so he informs the responsible authority with the aim of rectification.

As for the ruling on the salary, it has no relation to spying. The salary is permissible as long as the employee does not neglect his work and the contract is for a permissible job, not for prohibited spying.