After Draupadi's humiliating disrobing attempt, she vowed to keep her hair untied until it could be washed with Dushasana's blood. After the war, Bhima killed Dushasana, brought his blood, and fulfilled Draupadi's vow by washing her hair with it. Duryodhana, Karna, and Ashwathama were not the specific targets of this vow.