(13) But he said, “Please, O Lord, make someone else Your agent.”
(14) The Lord became angry with Moses, and He said, “There is your brother Aaron the Levite. He, I know, speaks readily. Even now he is setting out to meet you, and he will be happy to see you.
(15) You shall speak to him and put the words in his mouth — I will be with you and with him as you speak, and tell both of you what to do —
(16) and he shall speak for you to the people. Thus he shall serve as your spokesman, with you playing the role of God to him,
(17) And take with you this rod, with which you shall perform the signs.”
(13) But he said, “Please, O Lord, make someone else Your agent”: Once again Moses refuses the mission of leading the Exodus, but this time he offers no reason for his refusal. The point here is that the reasons Moses has given for his previous refusals, although they may have appeared reasonable, were essentially without merit. Rather, those refusals were due to Moses simply not wanting to lead the Jews out of Egypt.
(14) The Lord became angry with Moses: Until now, each time Moses refused the mission God would explain to him why he was wrong. But this time God uses a display of anger to impress upon Moses that an attitude adjustment is long overdue.
And He said, “There is your brother Aaron the Levite. He, I know, speaks readily”: Here we meet Moses’ brother Aaron for the first time, introduced from first mention as a prominent personality. He holds the position, as it were, of “Chief Rabbi of the Egyptian Jewish community.”
Aaron, unlike Moses, remained close to the people throughout his entire life. He was not raised in Pharaoh’s palace, nor did he spend many years in Midian. At the giving of the Torah, Aaron remained with the people at the foot of the mountain, and throughout the years in the wilderness he lived near the people. Aaron’s virtues and also his shortcomings all derive from this point. Because of his closeness to the people, Aaron has good communication with them, and can serve as an effective instrument for conveying Moses’ message to the people. But on the other hand, it is precisely Aaron’s closeness to the people that brings him to create the golden calf, thereby demonstrating that he is unworthy of becoming a national leader.
Even now he is setting out to meet you, and he will be happy to see you: Aaron’s most important quality is that he readily and willingly accepts Moses’ leadership, notwithstanding that Moses is his younger brother. We will consider this in greater detail below.
(15) You shall speak to him and put the words in his mouth — I will be with you and with him as you speak, and tell both of you what to do: Earlier (v. 12) God said to Moses, “I will be with you as you speak,” but now “I will be with you and with him as you speak, and tell both of you what to do.” At first it was assumed that Moses alone would lead the Exodus, but now the leadership will be divided between Moses and Aaron. This is a consequence of God’s anger over Moses’ repeated refusals.
(16) And he shall speak for you to the people. Thus he shall serve as your spokesman: Aaron does not stand on the same level as Moses. He is only an adjunct to Moses.
With you playing the role of God to him: Although the Hebrew word Elohim is one of God’s primary names, it can also refer more generally to a variety of other agents of superior authority. In particular, the word Elohim can be grammatically declined (which demonstrates that its meaning is relative, not absolute) and can also mean judges, heavenly powers, false gods, and the like. But as applied to the Almighty, this term is descriptive and impersonal, representing Him as the universally sovereign God.
Seen in that context, no deification of Moses is happening here; instead, his elevated status is emphasized. But even so, we find that in some aspects Moses was actually a “God” to the people. When Moses fails to return at the expected time from his forty days with God at the summit of Mount Sinai, the people “make a god” for themselves (in the form of the golden calf) to replace Moses, as they see it. We will examine this issue in greater detail below.
(17) And take with you this rod, with which you shall perform the signs: Moses must “not let the staff out of his hands,” he must maintain power, because without his leadership Aaron can easily be mistaken (which is what happened in the incident of the golden calf).
 In contrast, the four-letter Divine Name (YHWH, the Tetragrammaton) is absolute. Grammatically it cannot be declined, and is used to refer to the Almighty exclusively, expressing the aspect of “the God of the covenant.”