Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 15: The Demigods Appeal to the Lord for Protection
Text 1.15.14

नाकीर्तयदवज्ञानात्तद्रक्षो मानुषांस्तदा।
तस्मात्स मानुषाद्वध्यो मृत्युर्नान्योऽस्य विद्यते॥

nākīrtayad avajñānāt tad rakṣo mānuṣāṁs tadā
tasmāt
sa mānuṣād vadhyo mṛtyur nānyo ’sya vidyate

na = not; akīrtayat = did talk; avajñānāt = as he dishonored them; tat = that; rakṣaḥ = rākṣasa; mānuṣān = about men; tadā = at the time of seeking a benediction from me; tasmāt = therefore; saḥ = he; mānuṣāt = by a man; vadhyaḥ = can be killed; mṛtyuḥ na anyaḥ asya vidyate = no one else can kill him.

At the time of seeking a benediction from me, that rākṣasa did not talk about men as he dishonored them. Therefore, he can be killed by a man. No one else can kill him.