So this explains the title of Nick Cave’s And the Ass Saw the Angel:

A long and seriously bizarre episode about Moabite King Balak and the seer Balaam. The story goes like this: Balak, fearing the Israelite army, sends messengers to Balaam, asking him to curse the Israelites. Balaam consults with God, who orders him not to help Balak: “You must not curse that people, for they are blessed.” So, Balaam refuses Balak. But the king won’t take no for an answer. Balaam consults God again, who tells him to go to Balak but to obey the Lord’s orders.

At this point, the story is interrupted by perhaps the most inexplicable incident in the Bible so far. God is apparently irked at Balaam for accepting Balak’s invitation—even though God Himself told him to accept it—and blocks Balaam’s way with an invisible angel. Balaam keeps urging his ass forward, but the angel won’t let the animal pass. Balaam beats the ass, who proceeds to open her mouth and protest, “What have I done to you that you have beaten me?” The Lord reveals the angel to Balaam, who apologizes (though not to the ass).