Is one sinful if one gives a worker an amount deemed sufficient for an inspection service, but the worker refuses to waive the remaining amount he demands, knowing that the requested wage exceeds what is customary and was not agreed upon beforehand?

If a person performs work for another without an agreement on wages, and the worker is accustomed to working for wages, then he is entitled to a wage equivalent to that customarily given for such work (ajr al-mithl). This equivalent wage is determined by consulting experts in the field of maintenance, who assess the value of the work performed. These experts must be fair and unbiased, and it is preferable for their assessment to be made in the presence of both parties.