For further information on this painting, please see the Staatliche Kunstsammlungen Dresden webpage on this painting.
Narrative is from Exodus, 17:8-13.
Note that in the sale of Jan's estate there is listed "Een slach van Senacrip van vader selfs gedaen" -- so there was another Old Testament battle scene, that one from II Kings 17-19. It is also possible that the picture in Jan's sale is the present work and was just misidentified there. See Denuce, Brieven en documenten, 141. Jan's colleague Frans Francken also painted Old Testament battle scenes, and the subject can also sometimes be found in 16th and 17th-century Antwerp inventories.