Shloka 1.25.19
ताटकावृत्तान्तः — The Account of Tāṭakā and the Royal Duty to Protect
श्रूयते हि पुरा शक्रो विरोचनसुतां नृप।पृथिवीं हन्तुमिच्छन्तीं मन्थरामभ्यसूदयत्।।।।
śrūyate hi purā śakro virocana-sutāṃ nṛpa | pṛthivīṃ hantum icchantīṃ mantharām abhyasūdayat ||
It is indeed heard, O prince, that long ago Śakra (Indra) slew Mantharā, daughter of Virocana, when she sought to destroy the earth.
O Prince It is heard that in the past Indra slew Manthara, Virochana's daughter who intended to destroy the earth.
Appeal to dharmic precedent: even divine rulers act to prevent catastrophic harm; protection of the world overrides ordinary hesitation.
To remove Rāma’s scruple, Viśvāmitra cites an ancient example where Indra killed a destructive female being.
Commitment to loka-saṃgraha (upholding the world’s welfare) through decisive action.