'Oxen,' as in Exodus 9:3, signify exterior natural good.

(Notae: Arcana Coelestia 7503)

9. The third state is one of repentance, a state in which he speaks piously and devoutly from the internal man and brings forth goods, like charitable acts which are nevertheless inanimate since he imagines that they originate in himself. They are called a tender plant, then a seed-bearing plant, and finally a fruit tree.