Arjuna Battles the Nivatakavachas with Vajra
The Nivatakavachas retreat into their city, become invisible, and shower rocks from sky and earth, restraining Arjuna's horses and chariot. Oppressed and scared, Arjuna hears Matali's command: unleash the vajra weapon. He does — and his arrows become like the vajra itself, penetrating every maya and striking the danavas down.
Invisible, the daityas fought Arjuna with maya (illusion). With the power of invisible weapons, he continued to fight them. The shafted arrows from Gandiva, empowered with mantras, sliced off their heads wherever they were.
Thus killed by Arjuna in battle, the Nivatakavachas suddenly withdrew their maya and retreated into their city again. With the daityas having fled and everything visible once more, Arjuna saw the dead danavas there — in hundreds and thousands. Shattered weapons and ornaments lay everywhere. Heaps of dead bodies and armour could be seen. There was no room for the horses to move their feet.
Then the Nivatakavachas rose up suddenly and took to the sky. Invisible, they covered the entire sky and showered down large rocks. Other terrible danavas entered the interiors of the earth and restrained the feet of the horses and the wheels of the chariot. While engaged in the fight, they seized the tawny horses and the chariot and covered Arjuna — ascended on the chariot — in every direction with rocks.
Because of the rocks that covered him, and because of the others that kept falling, the entire region where they were stationed looked like a cave. Arjuna was sorely oppressed, enveloped with rocks. The horses had been restrained.
Matali noticed that Arjuna was scared.
"O Arjuna! O Arjuna! Do not be frightened. Discharge the vajra weapon."
Hearing these words, Arjuna unleashed the vajra weapon — the vajra that is loved by the king of the gods. He resorted to an immobile spot and invoked Gandiva with the mantra. He discharged sharp iron arrows that had the force of the vajra.
Having been discharged from the vajra, those arrows became like the vajra themselves. They penetrated all the maya of the Nivatakavachas. Struck by the vajras, those danavas clung to one another and fell down on the ground, like mountains. The arrows hunted out the danavas who had entered the interiors of the earth and had seized the horses and the chariot, and dispatched them to Yama's abode.
That place was littered with the corpses of mountainous Nivatakavachas, as if strewn with mountains. And it was extraordinary that the horses, the chariot, Matali, and Arjuna himself did not suffer any injury. Aranyaka Parva, Chapter 466