BG 6.21-23
That in which he findeth the supreme delight which the Reason can grasp beyond the senses, wherein established he moveth not from the Reality; Which, having obtained, he thinketh there is no greater gain beyond it; wherein, established, he is not shaken even by heavy sorrow; That should be known by the name of yoga, this disconnection from the union with pain. This yoga must be clung to with a firm conviction and with undesponding mind.