A very young Kunti had looked after Sage Durvasa when he was staying with them. Sage Durvasa gave her a divine mantra and said, "You can invoke any god by chanting this mantra, and he will appear before you and bless you with a son like him."
One day, Kunti decided to test the divine mantra.
She chanted the mantra to invoke Surya, the Sun-god. It was evening, suddenly, there was brilliant light all over. Kunti was blinded by the dazzling light. When she opened her eyes, she saw Surya, the Sun-god standing before her!
The Sun-god said, "You wish to have a son, and so you invoked me by chanting the mantra. I have come here to give you a son."