Is it permissible to accept a gift (incentive grant) from a spare parts vendor, knowing that the buyer is a responsible employee in a company and has generated profit for both the company and the vendor through his dealings with him?

The incentive grant mentioned is from the gifts given to workers, and it has been authentically narrated from the Prophet, peace and blessings be upon him, that gifts to workers are considered embezzlement (ghulul), and that whoever is appointed to a task should bring all of its aspects, minor and major; what he is given from it, he takes, and what he is prohibited from, he refrains from. Based on this, it is not permissible to accept or take it except with the permission of the employer. What the questioner did, by obtaining a lower price quote than what is due to him as part of his obligatory work, does not entitle him to take a grant for it.