Srimad Bhagavatam Canto 04, Chapter 19, Text 30

SB 4.19.30

na vadhyo bhavatam indro
yad yajño bhagavat-tanuh
yam jighamsatha yajñena
yasyestas tanavah surah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Brahma addressed them thus: My dear sacrificial performers, you cannot kill Indra, the King of heaven. It is not your duty. You should know that Indra is as good as the Supreme Personality of Godhead. Indeed, he is one of the most powerful assistants of the Personality of Godhead. You are trying to satisfy all the demigods by the performance of this yajña, but you should know that all these demigods are but parts and parcels of Indra, the King of heaven. How, then, can you kill him in this great sacrifice?