Srimad Bhagavatam Canto 09, Chapter 08, Text 12

SB 9.8.12

na sadhu-vado muni-kopa-bharjita
 nrpendra-putra iti sattva-dhamani
katham tamo rosamayam vibhavyate
 jagat-pavitratmani khe rajo bhuvah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
It is sometimes argued that the sons of King Sagara were burned to ashes by the fire emanating from the eyes of Kapila Muni. This statement, however, is not approved by great learned persons, for Kapila Muni’s body is completely in the mode of goodness and therefore cannot manifest the mode of ignorance in the form of anger, just as the pure sky cannot be polluted by the dust of the earth.
Srimad Bhagavatam Canto 09, Chapter 08, Text 11
Srimad Bhagavatam Canto 09, Chapter 08, Text 13