Is it permissible not to pay the installment for a semester of private tutoring from which no benefit was gained, relying on understanding from other sources, given the tutor's lack of attention to students and their assignments? And is it possible to delay payment without his knowledge?

The student must pay the tuition fees, based on the words of Allah Almighty: "Fulfill [your] contracts," and the words of the Prophet (peace be upon him): "Muslims are bound by their conditions." It is not permissible to default on payment under the pretext of not understanding. If the teacher demands payment and the student is able, he must pay immediately, based on the Prophet's saying: "The delay in payment by a rich person is oppression." However, if the teacher does not demand payment, scholars have differed regarding the obligation of performance. Some are of the view that it is not obligatory before a demand is made, while others hold that it is obligatory in certain cases, such as fearing the loss of the payment or if the student knows that the right-holder is in need.