Srimad Bhagavatam Canto 09, Chapter 07, Text 14

SB 9.7.14

punar jata yajasveti
 sa pratyahatha so ’bravit
sannahiko yada rajan
 rajanyo ’tha pasuh sucih
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
When the teeth grew in again, Varuna came and said to Hariscandra, “Now you can perform the sacrifice.” But Hariscandra then said, “O King, when the sacrificial animal becomes a ksatriya and is able to shield himself to fight with the enemy, then he will be purified.”
Srimad Bhagavatam Canto 09, Chapter 07, Text 13
Srimad Bhagavatam Canto 09, Chapter 07, Text 15