Midrash sa Genesis 34:26: Midrash Tanchuma & Bereshit Rabbah

For in their anger they slew a man (Gen. 49:6). Did they slay only one man? Is it not written: And they came upon the city unawares, and they slew all the males (ibid. 34:25)? The fact is that they were all considered by the Holy One, blessed be He, and by them as one man, as Scripture states: And thou shalt smite the Midianites as one man (Judg. 6:16). Similarly, it states: The horse and its rider hath He thrown into the sea (Exod. 15:1).

“The thistle that was in the Lebanon sent to the cedar” (II Kings 14:9). “The thistle that was in the Lebanon” – this is Ḥamor, father of Shekhem; “sent to the cedar” – this is Jacob. “Give your daughter to my son as a wife” (II Kings 14:9) – “The soul of my son Shekhem longs for your daughter. [Please, give her to him as a wife]” (Genesis 34:8). But the beasts of the field…passed and trampled” (II Kings 14:9) – “They killed Ḥamor and Shekhem his son by the sword” (Genesis 34:26). Who caused it? “Dina, daughter of Leah…went out.”

“The two sons of Jacob, Simeon and Levi…took” – from the fact that it says Simeon and Levi, we know that they are Jacob’s sons. It is, rather, “Jacob’s sons” – that they did not take counsel from Jacob; “Simeon and Levi” – that they did not take counsel from one another. “Dina's brothers” – was she only the sister of the two of them? Was she not the sister of all the tribes? It is, rather, because they endangered their lives on her behalf, she is called by their name. Similarly, “Miriam the prophetess, Aaron’s sister” (Exodus 15:20) – was she [only] Aaron’s sister? Was she not sister of the two of them? It is, rather, because Aaron devoted himself on her behalf,²²He implored Moses to pray on Miriam’s behalf when she was afflicted with leprosy. that is why she is called by his name. Similarly, “And in the matter of Kozbi, daughter of the prince of Midyan, their sister” (Numbers 25:18) – was she [only] their sister? Was she not a member of their nation? It is, rather, because she gave her life on behalf of her nation, her nation was called by her name.
“Each man took his sword” – Rabbi Elazar says: They were thirteen years old.
“They slew Ḥamor and Shekhem his son by the sword, and took Dina from Shekhem’s house, and departed” (Genesis 34:26).
Shmuel asked Levi bar Sisi, he said to him: ‘What is that which is written: “And came upon the city confidently”?’ He said to him: ‘They were confident in the strength of the elder. Our patriarch Jacob did not want his sons to perform that act, but when his sons performed that act, he said: What, will I allow my sons to fall at the hand of the nations of the world. What did he do? He took his sword and his bow, stood at the entrance of Shekhem, and said: If the nations of the world come to confront my sons, I will battle against them.’ That is what he said to Joseph: “I have given to you one portion [shekhem] beyond your brothers…” (Genesis 48:22) – where do we find that our patriarch Jacob took his sword and his bow in Shekhem, as it is stated: “Which I took from the hand of the Emorite, with my sword and with my bow”? (Genesis 48:22) – “Ḥamor and Shekhem his son.”²³As a consequence of the actions of Simeon and Levi, who killed Ḥamor and Shekhem, Jacob took up his sword and bow.