Shemot 4:14

ויחר אף AND [THE LORD’S] WRATH GLOWED — Rabbi Joshua the son of Korcha said: wherever the term “and God’s wrath glowed” occurs in the Scriptures it leaves a definite impression (mention of punishment of some kind follows), but here no such result is mentioned, for we do not find that any punishment came upon Moses in consequence of that anger of God. Rabbi José said to him: As a matter of fact here, too, some definite result is mentioned, viz., הלא אהרן אחיך הלוי “Is not Aaron the Levite thy brother?” — which implies, that he was destined to be a Levite (an attendant on the priests) and not a priest, — and I intended that the priesthood should proceed from you. Now, however, this shall not be so, but he will be the Priest and you the Levite, as it is said, (I Chronicles 23:14) “But as for Moses the man of God his sons are named among the tribe of Levi” (Zevachim 102a). הנה הוא יצא לקראתך HE WILL BE GOING FORTH TOWARDS THEE, when you will be going to Egypt. וראך ושמח בלבו AND WHEN HE SEETH THEE, HE WILL BE GLAD IN HIS HEART — not as you believe, that he will be angry with you because you have attained a high position. In consequence of this, Aaron was privileged to wear the ornament of the breastplate which was placed over his heart (cf. Exodus 28:29) (Shabbat 139a; Exodus Rabbah 3:17).

וַיִּֽחַר־אַ֨ף יְהֹוָ֜ה בְּמֹשֶׁ֗ה וַיֹּ֙אמֶר֙ הֲלֹ֨א אַהֲרֹ֤ן אָחִ֙יךָ֙ הַלֵּוִ֔י יָדַ֕עְתִּי כִּֽי־דַבֵּ֥ר יְדַבֵּ֖ר ה֑וּא וְגַ֤ם הִנֵּה־הוּא֙ יֹצֵ֣א לִקְרָאתֶ֔ךָ וְרָאֲךָ֖ וְשָׂמַ֥ח בְּלִבּֽוֹ׃

And the anger of the Lord burned against Moshe, and he said, Is not Aharon the Levite thy brother? I know that he can speak well. And also, behold, he comes to meet thee: and when he sees thee, he will be glad in his heart.