I have my own businessThere is someone who is dealing with us constantlyWe are implementing services for his clientsOften, he pays after workBut now there is a lot of money worth of payment for more than 1 yearso, he owe us since long time.We do not believe that he will pay in terms of coming out with an excuse every time he does not have the money nowKnowing is clear to us later that he intended to travel on a journey to enjoy !The question now ..Is it permissible that we Finessed him during the implementation of new services to his customers for the fulfillment of our right to do?Knowing that it would be affected in this case is its client .. But he has taken the money of the service implementation, and he paid the full value of the executed us in advanceThus, the failure to implement the service through us will take a hit from its client ..Knowing that there is no link or connection between us and the client's own ..We deal directly with the person who has not pay us, and we are implementing services for his clients ..also, we are afraid in future to pay our rights, so, please tell us what to do?can we do that and take money by making the work Not useful for his clients?thanks

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Among the firm established rules in the Sharia is what Allah says (what means): {…and no bearer of burdens will bear the burden of another.} [Quran 6:164]

Therefore, it is not permissible at all for the wronged person to take the right of others and oppress them as a way of getting his right from the person who wronged him.

If the purpose of that trick is to stop implementing the services for that man's clients to pressure him to pay what he owes you, given that those clients will be harmed by the delay of their services, then this is not permissible, because this represents doing injustice to the clients and harming them unjustly.

Also, among the firm established rules in Islamic law is that: Harm is not removed by another harm.

Az-Zuhayli said: “The harm is to be removed in Islam unless removing it necessitates doing a similar harm to others; then, in this case, the harm is not to be removed with a similar harm nor a greater harm or even a lesser harm. So, the harm of a particular person is not removed by harming another person, because all people are dependents of Allah and He made them all equally deserving of respect.” [Al-Qawaa'id al-Fiqhiyyah wa Tatbeeqaatuha fi al-Mathaahib al-Arba’ah]

Allah knows best.