”…And Hashem said . ‘Behold Aharon your brother, the Levite… and also he is going out to meet you, and he will see you and rejoice in his heart’.” (4:14)
Hashem is promising Moshe that Aharon will not be concerned that Moshe is rising to prominence over him. Rashi says that from this quality Aharon merited to wear the Kohein Gadol’s breastplate adorning his heart.
It would appear simply that because Aharon displayed good midos of a good heart he merited to wear the breastplate on his heart. Perhaps there is a deeper idea. The main part of the breastplate was the stones in which the names of the Tribes of Yisrael were inscribed. The stones of the efod also had the names inscribed “for remembrance” as Rashi explains “ that Hashem should see the Tribes written before Him and remember their righteousness.”
However, one thing could diminish the merit of the Tribes: the sale of Yosef. To offset this blemish the bearer of the breastplate would need to have qualities the opposite of those which led to the sale.
What brought about the sale? The younger brother stirred up jealousy (on their level) by becoming the center and replacing the older ones. This was the trial of Aharon. For years he was the leader in Mitzrayim while the Jews suffered under terrible persecution. Moshe was not there. And now the younger brother comes to act as the leader, replacing the older brother. In a way, Aharon was facing the same challenge as Yosef’s brothers.
Aharon not only acted outwardly with joy at seeing his younger brother, but Hashem testified that he would rejoice in his heart. The heart of Aharon was the proper place to rest the breastplate because he demonstrated selfless love towards his brother and that would enable the stones of the breastplate to bring the merits of Yisrael before Hashem . (Imrei Yitzchak)
Rabbi Aron Rosenberg
Skokie Community Kollel