SB 9.1.17
bhagavan kim idam jatam
karma vo brahma-vadinam
viparyayam aho kastam
maivam syad brahma-vikriya
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
My lord, all of you are expert in chanting the Vedic mantras. How then has the result been opposite to the one desired? This is a matter for lamentation. There should not have been such a reversal of the results of the Vedic mantras.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In this age, the performance of yajña has been forbidden because no one can properly chant the Vedic mantras. If Vedic mantras are chanted properly, the desire for which a sacrifice is performed must be successful. Therefore the Hare Krsna chant is called the maha-mantra, the great, exalted mantra above all other Vedic mantras, because simply chanting the Hare Krsna maha-mantra brings so many beneficial effects. As explained by Sri Caitanya Mahaprabhu (Siksastaka 1):
ceto-darpana-marjanam bhava-maha-davagni-nirvapanam
sreyah-kairava-candrika-vitaranam vidya-vadhu-jivanam
anandambudhi-vardhanam prati-padam purnamrtasvadanam
sarvatma-snapanam param vijayate sri-krsna-sankirtanam
“Glory to the Sri Krsna sankirtana, which cleanses the heart of all the dust accumulated for years and extinguishes the fire of conditional life, of repeated birth and death. This sankirtana movement is the prime benediction for humanity at large because it spreads the rays of the benediction moon. It is the life of all transcendental knowledge. It increases the ocean of transcendental bliss, and it enables us to fully taste the nectar for which we are always anxious.”
Therefore, the best performance of yajña given to us is the sankirtana-yajña. Yajñaih sankirtana-prayair yajanti hi sumedhasah (Bhag. 11.5.32). Those who are intelligent take advantage of the greatest yajña in this age by chanting the Hare Krsna maha-mantra in congregation. When the Hare Krsna mantra is chanted by many men together, the chanting is called sankirtana, and as a result of such a yajña there will be clouds in the sky (yajñad bhavati parjanyah). In these days of drought, people can gain relief from scarcity of rain and food by the simple method of the Hare Krsna yajña. Indeed, this can relieve all of human society. At present there are droughts throughout Europe and America, and people are suffering, but if people take this Krsna consciousness movement seriously, if they stop their sinful activities and chant the Hare Krsna maha-mantra, all their problems will be solved without difficulty. In other processes of yajña there are difficulties because there are no learned scholars who can chant the mantras perfectly well, nor is it possible to secure the ingredients to perform the yajña. Because human society is poverty-stricken and men are devoid of Vedic knowledge and the power to chant the Vedic mantras, the Hare Krsna maha-mantra is the only shelter. People should be intelligent enough to chant it. Yajñaih sankirtana-prayair yajanti hi sumedhasah. Those whose brains are dull cannot understand this chanting, nor can they take to it.