Midrasch zu Jehoschua 5:14

Behold, I sent an angel before thee (Exod. 23:20). The Holy One, blessed be He, said to Moses: I will send an angel before you but not before them. Whereupon Moses replied: If you send it before me alone, I do not desire it. Rather Let the Lord, I pray thee, go in the midst of us (Exod. 34:9). Observe the difference between the early generations and the later ones. When the Holy One, blessed be He, said to Moses: Behold, I will send an angel before you, he replied: I desire no one but You, whereas, when Joshua the son of Nun beheld an angel, he prostrated himself on the ground, as it is said: And Joshua fell on his face to the earth, and bowed down. And he said to him: “Art thou for us, or for our adversaries?” (Josh. 5:13–14).

R. Isaac queried: What did the angel do when he heard the question: Art thou for us, or for our adversaries? He began to cry out from the nails of his feet (i.e., to weep uncontrollably), and he said to him: Nay, I am captain of the hosts of the Lord; I am now come (ibid.). Twice I have come to lead Israel, I am he who came in the days of Moses your master, and he rejected me because he did not wish me to accompany him, and now I have come once again. Forthwith Joshua fell on his face to the earth, and bowed down, and said unto him: What saith my lord unto his servant? (ibid., v. 14). However, though Moses rejected him, the Holy One, blessed be He, said to him: I send an angel before thee to keep thee by the way (Exod. 23:20), and, as well, before everyone who observes the law.