"While focusing within the kutastha steadily, offering the oblation of prana with Atma-Mantra (The Prana Yagna is also called Aantar Yoga - Internal sacrifice) and mind becomes introvert and enchanted with melodious bumble-bee sound and then amrita starts dripping from sahasrara.
The amrita (sudha) is to be offered by raising the tip of the tongue into the vaishwanara as instructed by Sri Gurudeva. Verily this is called Yagna."
~ Swami Pranabananda Paramahamsa from Pranab Gita 3:9, English translation, Yoga Niketan