When the Moavites were overcome with fear of the Israelites, they turned to Midyan in the hope of finding a solution. The Sages explain how these two nations cooperated here despite their long history of enmity, and they also explain the unique imagery that the Moavites employed in describing their fear of Israel.

But don’t you find that Midyanites battle the Moavites…and the enmity between them is eternal? This can be explained by means of a parable. To what can this matter be compared? It can be compared to two dogs who were fighting each other and a wolf came and attacked one of them. The dog not being attacked said: If I do not help the other dog, today the wolf will kill it, and tomorrow it will attack me. Therefore, Moav joined together with Bilam [who was a Midyanite]. Balak said about the Israelites: “Now this assembly will lick clean all our surroundings, as the ox licks clean the grass of the field” (Numbers 22:4). Just as the might of an ox is in its mouth, so too, the might of these Israelites is in their mouths [with their prayers]. Just as there is no sign of blessing from anything an ox chews [as the ox eats the produce with its roots,] so too these; any nation they touch, there is no sign of blessing from it. And just as an ox gores with its horns, so too, these gore with their prayers. (Tanĥuma, Balak)