As it is said, ‘And Aaron shall bear the names of the Israelites on the breastplate on his heart’” [Midrash Tanhuma]. Because of this capacity to rejoice wholeheartedly in another’s good ...

Because of this, Aaron merited אורים ותומים: the ornament of the breastplate, which is placed over the heart.’ The parshanim expound:Hashem said this to Moshe, to put his mind at rest ...