What is the ruling of the Shariah on reducing the wage of a carpenter who did not use the agreed-upon wood?

The transaction between the man and the carpenter is a manufacturing contract (Istisna‘). The carpenter is obligated to complete the work according to the terms of the contract. If the carpenter breaches the condition by using wood other than what was stipulated, the employer is not obliged to accept anything but the agreed-upon wood, as the Messenger of Allah, peace and blessings be upon him, said: "Muslims are bound by their conditions." If it is impossible to provide the stipulated wood, the contract can be terminated, or the terms and price can be amended by mutual consent. Alternatively, the person who commissioned the work may accept a different specification and a reduction in price if they both agree to it.