William Shakespeare (1564–1616), British dramatist, poet. Hamlet, in Hamlet, act 3, sc. 4, l. 190-1 (1604).
Referring to the untrustworthiness of Rosencrantz and Guildenstern. (These lines do not appear in the 1623 Folio edition.) A "petard" was an explosive device used by engineers of the time, and thus the expression has passed into common usage to mean "caught in one's own trap."