Genesis 34:5
And Jacob heard that he had defiled Dinah his daughter: now his sons were with his cattle in the field: and Jacob held his peace until they were come. And Jacob heard that he had defiled Dinah his daughter: now his sons were with his cattle in the field: and Jacob held his peace until they were come.
Dinah was the one daughter of Jacob's household. At Shechem a single rash youth by a lawless act brought her to shame and sorrow, and this defilement is what Jacob heard had happened. Jacob remained silent and held his peace until his sons came in from being with the cattle in the field.
Simeon and Levi by secret planning and deception took revenge by murdering and destroying the Shechemites, ruining and slaughtering a whole city in retaliation. Jacob had no part in the secret plan of Simeon and Levi. The defilement was real and provoked what followed, but it did not excuse the revenge. When Jacob heard of the revenge he was filled with horror and heart-sickness at their deceit, violence, and treacherous cruelty as a grievous sin.
His immediate response that he was troubled and made odious among the inhabitants of the land expressed fear that, because they were few in number, the peoples would gather against his house and destroy it. Nearly fifty years later on his deathbed in Egypt, his curse upon their fierce and cruel anger showed his continuing grief and abhorrence of the bloody deed.