Book of Judith
The episode of Judith beheading Holofernes is from a deuterocanonical book of the Bible. The episode is from the apocryphal Book of Judith in the Old Testament, which recounts the assassination of the Assyrian general Holofernes by the Israelite heroine Judith. Gentileschi draws upon the most climactic part of the Book of Judith where the beheading takes place.