Srimad Bhagavatam Canto 08, Chapter 11, Text 32

SB 8.11.32

na tasya hi tvacam api vajra urjito
 bibheda yah sura-patinaujaseritah
tad adbhutam param ativirya-vrtra-bhit
 tiraskrto namuci-sirodhara-tvaca
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Although King Indra hurled his thunderbolt at Namuci with great force, it could not even pierce his skin. It is very wonderful that the famed thunderbolt that had pierced the body of Vrtrasura could not even slightly injure the skin of Namuci’s neck.
Srimad Bhagavatam Canto 08, Chapter 11, Text 31
Srimad Bhagavatam Canto 08, Chapter 11, Text 33