Although the circulation and revision of Italian opera librettos is a well-known aspect of musical life in eighteenth-century Europe, the practice has hardly been touched upon with regard to the Italian oratorio of the same period. Librettist Apostolo Zeno (1668–1750) worked in and theorized about both genres, yet his involvement with the oratorio has been little studied. This article addresses three editions of an oratorio libretto by Domenico Canavese. Following versions for Florence (1712) and Pistoia (1714), a third appeared in 1726 in conjunction with a Lenten performance at the Imperial Court Chapel in Vienna. An annotated copy of the 1712 edition from Zeno's library shows that he revised the text for the Viennese performance. His textual changes – some small, some radical – reveal practical, stylistic and dramaturgical concerns. A comparison of the annotated copy with the printed libretto for the 1726 performance and the principal musical source for the new setting by Giuseppe Porsile shows that Zeno's revisions were scrupulously followed.