"And two of Jacob's sons took [Simeon and Levi]." From the implication of what is said, "Simeon and Levi," do I not know that they are the sons of Jacob? Rather, [it teaches that they are] the sons of Jacob who did not take counsel one from the other. "The brothers of Dinah." Now, was she the sister of these two and not the sister of the rest? Rather, because they gave themselves over on her behalf, she is called by their name. "And they came upon [the city] securely." They were secure in the strength of the old man. Jacob said: I will not leave my sons, that they should fall into the hand of the nations of the world who would join together against them; I will fight against them. This is what is written: "Which I took out of the hand of the Amorite with my sword and with my bow" (Genesis 18:22).
Simeon and Levi Strike Shechem Trusting in Jacob's Strength
Midrash Aggadah, Genesis 34:25
ויקחו שני בני יעקב [שמעון ולוי]. ממשמע שנאמר שמעון ולוי איני יודע שבני יעקב הם, אלא בני יעקב שלא נטלו עצה זה מזה: אחי דינה. וכי אחות שניהם ולא אחות השאר היתה, אלא לפי שנתנו עצמם עליה נקראת על שמם: ויבאו אל [העיר] בטח. בטוחים היו על כחו של זקן, אמר יעקב לא אניח בני אשר יפול בידי אומות העולם להזדווג עליהם, אני אלחם כנגדם, הדא הוא דכתיב אשר לקחתי מיד האמורי בחרבי ובקשתי (בראשית יח כב):