Krishna-Dwaipayana Vyasa, The Mahabharata, Book 1: Adi Parva…
“ And seeing that the snakes had multiplied exceedingly, the Grand-father moved by kind consideration for his creatures sanctioned with all the gods this curse of Kadru. Indeed, of flaming poison, great prowess, excess of strength, and ever bent on biting other creatures, in consequence of such poison and for the good of all creatures the conduct of their mother towards those persecutors of all creatures was very proper. Fate always inflicts the punishment of death on those who seek the death of other creatures. ”
