“The Lord said to Aaron: Go toward Moses to the wilderness. He went, and he met him at the mountain of God and he kissed him” (Exodus 4:27). “The Lord said to Aaron: Go toward Moses to the wilderness” – that is what is written: “If only you were as my brother [who nursed from the breasts of my mother; I would find you outside, I would kiss you]” (Song of Songs 8:1). Regarding which brother is the verse speaking?
If you say it is regarding Cain, but is it not written: “Cain rose against his brother Abel and killed him”? If you say it is like Ishmael to Isaac, did we not learn: Ishmael hates Isaac? If you say it is like Esau to Jacob, is it not written: “Esau hated Jacob” (Genesis 27:41)? If you say it is like Joseph’s brothers, but is it not written: “They hated him” (Genesis 37:4), and it is written: “His brothers envied him” (Genesis 37:11).
Rather, it is like Joseph to Benjamin, “who nursed from the breasts of my mother” (Song of Songs 8:1),1Joseph and Benjamin were from the same mother, Rachel, whereas their other brothers were not sons of Rachel. [and] like Moses to Aaron, as it is stated: “He went, and he met him at the mountain of God and he kissed him.” Our Rabbis, of blessed memory, said: All kisses are indecent except for three: The kiss of greatness, the kiss of separation, and the kiss of reunion.
The kiss of greatness, as it is stated: “Samuel took the vial of oil, and poured it upon his head, and kissed him” (I Samuel 10:1); the kiss of separation: “Orpa kissed her mother-in-law” (Ruth 1:14); the kiss of reunion, as it is stated: “He went, and he met him at the mountain of God and he kissed him.” Some say: Even a kiss of closeness is not disgraceful, as it is stated: “Jacob kissed Rachel” (Genesis 29:11), who was his relative.
Rabbi Pinḥas said: There was an incident involving a brother and a sister, one of whom was in Gush Ḥalav and one of whom was in Beit Maron. The house in Gush Ḥalav caught fire. His sister came from Beit Maron and fell upon him and was hugging him and kissing him. She said: ‘I am not accustomed to come to you [and to kiss you], but I was afraid, as you are my brother and were in distress, and you emerged from it.’
“I would find you outside, I would kiss you” (Song of Songs 8:1) – where outside? It is in the wilderness, where the brothers, Moses and Aaron, kissed each other.