The noun "oath" is an abstract noun that refers to a promise that the men made to God to kill Paul. It can also be made explicit what would happen to the men if they did not do what they had promised to do. Alternate translation: "asked God to curse them if they did not do what they promised" (See: [[rc://en/ta/man/translate/figs-abstractnouns]] and [[rc://en/ta/man/translate/figs-explicit]])