Is money earned from a job obtained by paying a bribe considered unlawful wealth, and must one leave working in this job?

A forbidden bribe is that by which falsehood is made to prevail or truth is nullified. As for what is given to attain a right, it is not considered a forbidden bribe on the part of the giver; rather, it is forbidden for the taker. If the position is a rightful employment for the questioner and cannot be obtained except by paying money, then there is no objection to it, as long as it is not at the expense of someone more deserving of the position. However, if the questioner is not qualified for the position, then what he paid is a forbidden bribe, and he must repent. His work and salary are lawful as long as he is qualified for the position and fulfills his duty.