SB 4.19.28
vayam marutvantam ihartha-nasanam
hvayamahe tvac-chravasa hata-tvisam
ayatayamopahavair anantaram
prasahya rajan juhavama te ’hitam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Dear King, Indra’s powers are already reduced due to his attempt to impede the execution of your sacrifice. We shall call him by Vedic mantras which were never before used, and certainly he will come. Thus by the power of our mantra, we shall cast him into the fire because he is your enemy.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
By chanting the Vedic mantras properly in a sacrifice, one can perform many wonderful things. In Kali-yuga, however, there are no qualified brahmanas who can chant the mantras properly. Consequently no attempt should be made to perform such big sacrifices. In this age the only sacrifice recommended is the sankirtana movement.