SB 4.19.28

vayaṁ marutvantam ihārtha-nāśanaṁ
 hvayāmahe tvac-chravasā hata-tviṣam
ayātayāmopahavair anantaraṁ
 prasahya rājan juhavāma te ’hitam
Synonyms: 
vayam — we; marut-vantam — King Indra; iha — here; artha — of your interest; nāśanam — the destroyer; hvayāmahe — we shall call; tvat-śravasā — by your glory; hata-tviṣam — already bereft of his power; ayātayāma — never before used; upahavaiḥ — by mantras of invocation; anantaram — without delay; prasahya — by force; rājan — O King; juhavāma — we shall sacrifice in the fire; te — your; ahitam — enemy.
Translation: 
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 chanting the Vedic mantras properly in a sacrifice, one can perform many wonderful things. In Kali-yuga, however, there are no qualified brāhmaṇas 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 saṅkīrtana movement.