What is the ruling on some teachers delegating others to teach on their behalf for a specified fee, while they receive the remainder of the salary, and sometimes they completely abstain from teaching or only conduct a few classes?

Workers are divided into two types: private and public. A private worker, such as a teacher or an employee whose work is measured by a specific time, is not allowed to delegate someone else in his place, because the hiring agreement is tied to his person, and he must fulfill the contract. As for a public worker, his benefit is measured by a task, like sewing a garment, and he is allowed to delegate someone else to perform the work. Therefore, a teacher is not permitted to appoint another person to do his work without the approval of the Ministry of Education or the education administration.