Δίκη δίκην ἔτικτε καὶ βλάβη βλάβην

[sc. A proverbial phrase] in reference to those who are litigious and piling up lawsuits one on the other.¹
Also, "to think of suing even if a donkey bites a dog". In reference to those who engage in malicious prosecuting on trivial matters.²