Paid in one’s own coin
This is an old proverb meaning that bad intentions or actions against others often backfire and result in bad consequences for the initiator. This concept runs through most of the ancient fables and is a recurring theme in the Bible and throughout literature. There are many sayings with similar meanings: reap as one’s sows, hoist on one’s own petard, do as you would be done by, get one’s just deserts etc. ‘Paid him in his own coin’ is cited in the 1703 English translation of Cervantes’ Don Quixote (Part I, Book III, Chapter IV).