Who provided the German libretto to the composition by a man whose best known work is "The Threepenny Opera," which proved to be their last major collaboration?
The Seven Deadly Sins (ballet chanté): The Seven Deadly Sins (German: "Die sieben Todsünden" , French: "Les sept péchés capitaux" ) is a satirical "ballet chanté" ("sung ballet") in seven scenes (nine movements) composed by Kurt Weill to a German libretto by Bertolt Brecht in 1933 under a commission from Boris Kochno and Edward James. The Seven Deadly Sins (ballet chanté):  It was the last major collaboration between Weill and Brecht. Kurt Weill:  With Brecht, he developed productions such as his best-known work "The Threepenny Opera", which included the ballad "Mack the Knife".
Bertolt Brecht