Mahabharata 6.48.63

6.48.63

na śakyau yudhi saṃrabdhau jetumetau mahārathau |
sadevāsuragandharvairlokairapi kathaṃcana || 63 ||

These mighty car-warriors when excited with rage, are incapable of ever being vanquished in battle by all the worlds with the gods, the Asuras and the Gandharvas. This highly wonderful battle would be wonderful in all the worlds. Indeed, a battle such as this will never take place again. Bhishma is incapable of being conquered in combat by Pritha's son of great intelligence, showering his arrows in battle, with bow and car and steeds. So also that great bowman, the son of Pandu, incapable of being vanquished in battle by the very gods, Bhishma is not competent to conquer in combat. As long as the world itself will last, so long will this battle continue equally. We heard these words, O king, fraught with the praise of Ganga's son and Arjuna in battle bruited about there. And while those two were engaged in displaying their prowess, other warriors of thy side and of the Pandavas, O Bharata, slew one another in battle, with sharp-edged scimitars, and polished battle-axes, and innumerable arrows, and diverse kinds of weapons. And the brave combatants of both armies cut one another down, while that terrible and murderous conflict lasted. And the encounter also, O king, that took place between Drona and the prince of the Panchalas, was awful."