A cruel and wretched person who maintains his existence at the cost of others’ lives deserves to be killed for his own well-being, otherwise he will go down by his own actions.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
स्वप्राणान् यः परप्राणैः प्रपुष्णात्यघृणः खलः । तद्वधस्तस्य हि श्रेयो यद्दोषाद्यात्यधः पुमान्
svaprāṇān yaḥ paraprāṇaiḥ prapuṣṇātyaghṛṇaḥ khalaḥ | tadvadhastasya hi śreyo yaddoṣādyātyadhaḥ pumān
SB 1.7.37