Must I pay the remaining dues to the engineer who carried out poor maintenance work on my house, knowing that the agreement was not to pay in the event of poor maintenance, and that I paid him half the amount out of consideration for my friend who introduced me to him?

The hiring of a worker here is of the type of a general employee (ajir amm), who is hired for a specific task and not for a duration. He is entitled to the wage upon completion of the agreed-upon work in the required manner. If there is a deficiency or incomplete work, the hirer has the right to deduct an amount corresponding to the shortage, which is to be determined by experts.

As for the questioner, the two scenarios are: 1. If she accepted the maintenance despite the deficiency and committed to payment, then it is not permissible for her to refuse payment after her acceptance. 2. If she did not accept the deficiency and did not commit to paying the full amount, then she is not obligated to fulfill the promise by the amount of the deficiency in the maintenance, although fulfilling the promise is better.