שבת קל״ט א:י״ד
And Rabbi Mallai said: It is stated in the verse: “And the anger of the Lord was kindled against Moses, and He said: Is there not Aaron your brother the Levite, I know that he can surely speak, and also behold, he is coming out to greet you, and he will see you and be glad in his heart” (Exodus 4:14). Rabbi Mallai taught that as reward for Aaron’s lack of jealousy at seeing his brother Moses rise to greatness, as it is stated: “And he will see you and be glad in his heart,” he merited to become the High Priest, and for the breastplate of judgment to rest on his heart.
רש"י על שבת קל״ט א:י״ד:א׳
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בן יהוידע על שבת קל״ט א:ט׳
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חידושי אגדות על שבת קל״ט א:ז׳
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