Mahabharata Mausala Parva Chapter 3:3

Mahabharat Mausala-Parva Chapter 3:3 That handful of grass became a terrible bolt of iron endued with the energy of the thunderbolt. With it Krishna slew all those that came before him. Then the Andhakas and the Bhojas, the Saineyas and the Vrishnis, urged by Time, struck one another in that fearful melee. Indeed, O king, whoever amongst them took up in wrath a few blades of the Eraka grass, these, in his hands, became soon converted into a thunderbolt, O puissant one. Every blade of grass there was seen to be converted into a terrible iron bolt. All this, know, O king, was due to the curse denounced by Brahmanas. He who hurled a blade of grass saw that it pierced through even such things as were utterly impenetrable. In fact, every blade was seen to become a terrible bolt having the force of thunder. Son killed sire, and sire killed son, O Bharata. Inebriated with wine, they rushed and fell upon one another. The Kukuras and the Andhakas met with destruction like insects rushing at a blazing fire. As they were thus being slaughtered, no one among them thought of escaping by flight. Knowing that the hour of destruction had come, the mighty-armed Keshava stood there, eyeing everything. Indeed, the slayer of Madhu stood, raising a bolt of iron formed of a blade of grass. Beholding that Samva was slain, as also Charudeshna and Pradyumna and Aniruddha, Madhava became filled with rage. Beholding Gada lying dead on the ground, his wrath became enhanced. The wielder of Sarnga and the discus and the mace then exterminated the Vrishnis and the Andhakas. Hear, O king, what that conquerer of hostile towns, Vabhru of mighty energy and Daruka then said to Krishna, "O holy one, a very large number of men has been slain by thee. Turn now to where Rama has gone. We wish to go there where he has proceeded.