Midrasch zu Jehoschua 24:12

(Deut. 2:31): SEE I HAVE BEGUN TO GIVE <SIHON AND HIS LAND> OVER TO YOU (in the singular). He did not say: "To you (in the plural)," but TO YOU (in the singular), <i.e.,> because of you (in the singular). Now it was not because Israel possessed good works that I handed them over, but because of you. Moses said: You are sending an Angel. I have no need for him, (in the words of Exod. 33:15) IF YOUR PRESENCE DOES NOT GO ALONG. The Holy One said: Is it because of the angel that you are making a complaint? By your life, it shall not be an angel but a single hornet that I will send, and it shall finish them; for so it says (in Josh. 24:12): I SENT THE HORNET BEFORE YOU, <WHICH DROVE OUT THOSE TWO KINGS OF THE AMORITES FROM BEFORE YOU>.