Genesis 34:25
And it came to pass on the third day, when they were sore, that two of the sons of Jacob, Simeon and Levi, Dinah’s brethren, took each man his sword, and came upon the city boldly, and slew all the males. And it came to pass on the third day, when they were sore, that two of the sons of Jacob, Simeon and Levi, Dinah’s brethren, took each man his sword, and came upon the city boldly, and slew all the males.
Genesis 34:25 describes a planned revenge by Simeon and Levi, Dinah's brothers, for the violation of their sister. The attack was carried out through deception and treachery. On the third day, while the men of the city were sore from circumcision, the two brothers each took his sword, came upon the city boldly, and slew all the males, bringing ruin and bloodshed upon the city.
Their revenge was not unprovoked, yet the treachery and violence were grievous sins, cruel and revengeful. God did not sanction or approve their conduct. Jacob did not know their plan until the violence was complete. He reproved them because the deed put him and his household at risk of retaliation from the surrounding nations. He reproved them because their actions had made him despised and exposed his household to danger.
Jacob later condemned their fierce anger and cruel wrath for this cruelty. He foretold that their descendants would be divided and scattered in Israel. Simeon and Levi were among the sons most guilty in the case of Joseph. Their earlier cruelty at Shechem explains why Jacob feared evil had happened to his sons when they were near the city.