Aaron Rejoiced in His Brother and Wore the Breastplate

(Exodus 4:13-14) "Send, I pray, by the hand of him whom You will send" (Exodus 4:13). You might think that Moses was holding back so as not to go - he did nothing but honor Aaron. Moses said: Before I arose, my brother Aaron was prophesying to them for eighty years; this is what is written, "and I made Myself known to them in the land of Egypt" (Ezekiel 20:9). And from where that Aaron was prophesying to them? As it is said (1 Samuel 2:27-28), "And a man of God came to Eli and said to him, Thus says the LORD: Did I not reveal Myself to the house of your father when they were in Egypt in the house of Pharaoh, and choose him out of all the tribes of Israel to be My priest?" He said: All these years Aaron was prophesying to them; now I am coming into my brother's domain and he will be distressed. For this reason Moses did not wish to go. The Holy One, blessed be He, said to him: Aaron your brother is not distressed by this matter; rather he will rejoice. Know this, that he is going out to meet you, as it is said, "behold, he is coming out to meet you, and when he sees you he will rejoice in his heart" - not with his mouth but in his heart; in his heart more than in his mouth. Rabbi Shimon ben Yochai said: The heart that rejoiced in the greatness of his brother shall wear the Urim and Tummim, as it is said, "and you shall put into the breastplate of judgment the Urim and the Tummim, and they shall be upon Aaron's heart" (Exodus 28:30). When the Holy One, blessed be He, said this to him, he accepted upon himself to go. Immediately the Holy One, blessed be He, was revealed to Aaron and said to him: Go out to meet Moses your brother so that he will know you rejoice in this matter; therefore it is said, "to meet Moses toward the wilderness" (Exodus 4:27). Had Aaron known (it is written in remez 142).