Srila Prabhupada writes in Krishna: "According to the Vedic system, whenever there is an arrangement for sacrifice, the members participating in the sacrifice are offered the juice of the soma plant. The juice of the soma plant is a kind of life-giving beverage. On the day of extracting the soma juice, King Yudhishthira very respectfully received the special priest who had been engaged to detect any mistake in the formalities of sacrificial procedures. The idea is that the Vedic mantras must be enunciated perfectly and chanted with the proper accent; if the priests who are engaged in this business commit any mistake, the checker, or referee priest, immediately corrects the procedure, and thus the ritualistic performances are perfectly executed. Unless it is perfectly executed, a sacrifice cannot yield the desired result. In this age of Kali there is no such learned brahmana or priest available; therefore, all such sacrifices are forbidden. The only sacrifice recommended in the sastras is the chanting of the Hare Krishna mantra."