Srimad Bhagavatam Canto 04, Chapter 05, Text 24

SB 4.5.24

drstva samjñapanam yogam
pasunam sa patir makhe
yajamana-pasoh kasya
kayat tenaharac chirah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Then Virabhadra saw the wooden device in the sacrificial arena by which the animals were to have been killed. He took the opportunity of this facility to behead Daksa.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
In this connection it is to be noted that the device used for killing animals in the sacrifice was not designed to facilitate eating their flesh. The killing was specifically intended to give a new life to the sacrificed animal by the power of Vedic mantra. The animals were sacrificed to test the strength of Vedic mantras; yajñas were performed as a test of the mantra. Even in the modern age, tests are executed on animal bodies in the physiology laboratory. Similarly, whether or not the brahmanas were uttering the Vedic hymns correctly was tested by sacrifice in the arena. On the whole, the animals thus sacrificed were not at all the losers. Some old animals would be sacrificed, but in exchange for their old bodies they received other, new bodies. That was the test of Vedic mantras. Virabhadra, instead of sacrificing animals with the wooden device, immediately beheaded Daksa, to the astonishment of everyone.
Srimad Bhagavatam Canto 04, Chapter 05, Text 23
Srimad Bhagavatam Canto 04, Chapter 05, Text 25