SB 8.11.37

iti śakraṁ viṣīdantam
 āha vāg aśarīriṇī
nāyaṁ śuṣkair atho nārdrair
 vadham arhati dānavaḥ
Synonyms: 
iti — in this way; śakram — unto Indra; viṣīdantam — lamenting; āha — spoke; vāk — a voice; aśarīriṇī — without any body, or from the sky; na — not; ayam — this; śuṣkaiḥ — by anything dry; atho — also; na — nor; ārdraiḥ — by anything moist; vadham — annihilation; arhati — is befitting; dānavaḥ — this demon (Namuci).
Translation: 
Śukadeva Gosvāmī continued: While the morose Indra was lamenting in this way, an ominous, unembodied voice said from the sky, “This demon Namuci is not to be annihilated by anything dry or moist.”