Srimad Bhagavatam Canto 08, Chapter 11, Text 33

SB 8.11.33

tasmad indro ’bibhec chatror
 vajrah pratihato yatah
kim idam daiva-yogena
 bhutam loka-vimohanam
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
When Indra saw the thunderbolt return from the enemy, he was very much afraid. He began to wonder whether this had happened because of some miraculous superior power.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Indra’s thunderbolt is invincible, and therefore when Indra saw that it had returned without doing any injury to Namuci, he was certainly very much afraid.
Srimad Bhagavatam Canto 08, Chapter 11, Text 32
Srimad Bhagavatam Canto 08, Chapter 11, Text 34