To be harmed by the very device or plot one had intended for another.

खुद के जाल में फंस जाना।

English Usage: He tried to discredit his competitor, but instead, he was hoist with his own petard when his dishonest methods were exposed.

Hindi Usage: उसने अपने प्रतियोगी को बदनाम करने की कोशिश की, लेकिन जब उसकी बेईमानी उजागर हुई, तो वह खुद के जाल में फंस गया।