Srimad Bhagavatam Canto 04, Chapter 04, Text 32

SB 4.4.32

tesam apatatam vegam
nisamya bhagavan bhrguh
yajña-ghna-ghnena yajusa
daksinagnau juhava ha
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
They came forward forcibly, but Bhrgu Muni saw the danger and, offering oblations into the southern side of the sacrificial fire, immediately uttered mantric hymns from the Yajur Veda by which the destroyers of yajñic performances could be killed immediately.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Here is one example of powerful hymns in the Vedas which, when chanted, could perform wonderful acts. In the present Age of Kali it is not possible to find expert mantra chanters; therefore all the sacrifices recommended in the Vedas are forbidden in this age. The only sacrifice recommended in this age is the chanting of the Hare Krsna mantra because in this age it is not possible to accumulate the needed funds for performing sacrifices, not to speak of finding expert brahmanas who can chant the mantras perfectly.
Srimad Bhagavatam Canto 04, Chapter 04, Text 31
Srimad Bhagavatam Canto 04, Chapter 04, Text 33