When Vasundharā, the Earth goddess, heard the words of Nārāyaṇa, she was filled with wonder and amazement. She spoke with reverence, saying, “O Lord, I have heard that your followers are deeply devoted to your sacred rites. But tell me, in what kind of recipients should the acts you prescribe be performed?” Nārāyaṇa, the Lord of the world, listened to her question and responded graciously, “O Earth, I will explain to you all that you have asked. Of all materials here, copper is especially pleasing to me.” Then the Earth, in her devotion, addressed Janārdana, the Lord of the worlds, with sweet words. Hearing her inquiry, the beginningless and unconquered Lord spoke again, “Listen carefully, O sinless one, as I reveal the truth to you. “In the beginning, O Mādhavī, there were seven thousand yugas. In those ancient times, O lotus-eyed one, there lived the great asura Guḍākeśa. He worshipped me with unwavering devotion for fourteen years. Through his intense austerity and steadfast resolve, he won my favor. “O great goddess, I visited his hermitage, and hearing his auspicious words, I was pleased. Appearing before him in my four-armed form, devoted to my duties, I spoke to him with a joyful heart: ‘O Guḍākeśa, most fortunate one, tell me—what boon shall I grant you? Whatever you desire, whether in deed, thought, or word, speak it now.’ “Guḍākeśa, hearing my words, replied: ‘If you are truly pleased with me, O Lord, with all your heart, then I desire to be slain by you, O Keśava, with your discus. And after I am struck down by your discus, what shall become of my flesh and marrow?’ “Then, with his virtuous mind, he requested that a vessel be fashioned from his flesh and marrow, so that, once an offering was made in it, his mind would be supremely satisfied. “O Lord of the gods, having contemplated this while standing firm in severe austerity, I granted his wish: ‘You shall remain established in my presence, assuming a form stationed upon copper. Whatever is offered to me in a copper vessel, filled to the brim, that copper is auspicious and pure—this is why it is dear to me. “On the twelfth day of the bright fortnight in the month of Vaiśākha, you shall come to my world—there is no doubt about this.’ “Desiring to be struck down by my discus, Guḍākeśa remained steadfast in my service. When the bright fortnight arrived, established in righteousness, he called out, ‘Release, release, O Lord, even the discus shining like fire!’ Then, pierced by the discus, he attained my presence, becoming foremost among devotees. “As for other metals—tin, lead, zinc, bronze, and iron—these are impure, and impurity is inherent in them. But whatever is offered to me in a copper vessel upon the earth should always be performed by my dear devotees, the Bhāgavatas. “Those Bhāgavatas who have been properly initiated should offer water for washing the feet, and arghya, and other offerings using copper vessels. O goddess, I have explained this to you truthfully. What else do you wish to ask?” Vasundharā then inquired, “O Lord of gods, tell me how an initiated person should perform the twilight worship. By which mantra does your devoted follower, intent on action, perform it?” Nārāyaṇa replied, “Listen, Mādhavī, to the supreme mantra for twilight worship, as it truly is. Just as my devotees worship the Sun, so too should they worship during both the former and later twilights. Assuming a meditative posture, even for a moment, one should recite this mantra.