Śānti-parva Adhyāya 3: Karṇa’s training under Rāma Jāmadagnya and the Bhārgava restriction on the Brahmāstra
यस्मान्मिथ्योपचरितो हास्त्रलो भादिह त्वया । तस्मादेतद्ि ते मूढ ब्रह्मास्त्रं प्रतिभास्यति
yasmān mithyopacarito hāstralo bhād iha tvayā | tasmād etad i te mūḍha brahmāstraṃ pratibhāsyati ||
Nārada said: “Since you have here treated that weapon with false and improper handling, therefore, O deluded one, this Brahmā-weapon will turn back upon you and appear against you.”
नारद उवाच
Power—especially sacred or extraordinary power—demands correct discipline and truthful, proper practice. When handled wrongly (mithyā-upacāra), it rebounds upon the user, showing that adharma and negligence carry self-destructive consequences.
Nārada warns the addressed person that, because the weapon has been improperly handled, the Brahmāstra will not serve as intended; instead it will manifest against the very one who tried to wield it, turning the act into a punishment and a moral lesson.