Working in Contravention of Contracts

Your Eminence! A man brought in a worker to work for him in herding. This guarantor took over the work,Meaning: seeing that the work assigned to this worker was little, so he had him do many other jobs,Among them: such as contracting with some of the owners of rest houses to clean their rest houses, or with some of the mosques to lay out and clean them for a salary. So, when he first brought in this worker, he contracted with him for a salary of, for example, six hundred riyals. At the end of the month, this worker does temporary work in the mosques and some of the rest houses, so at the end of the month he earns approximately one thousand riyals. The guarantor takes it and gives this worker six hundred riyals, even though he takes four hundred riyals, and puts it in his pocket, even though this worker works for him in addition to the tasks he is assigned, and says: that he is satisfied. What is the ruling on that?
As long as the worker is satisfied with that without coercion, there is no harm.Even if the worker says: I work for you for free without coercion, so there is no harm.But if it is with coercion, such that he says to him: Either you do this extra work beyond what is in the contract, or you leave; this is not permissible. Rather, it is obligatory for him to restrict himself to what they agreed upon beforehand;because of His saying, the Exalted: [Al-Ma'idah: 1] .

The questioner: Regarding the increase in the salary?Answer: There is no obstacle to the increase being for the guarantor, as long as the worker is satisfied with this.