Pururava was a good king who performed many yajnas. He ruled the earth well. Urvashi was a beautiful apsara. Pururava met Urvashi and fell in love with her.
―Please marry me,‖ he requested.
―I will,‖ replied Urvashi, ―But there is a condition. I love these two sheep and they will always have to stay by bedside. If I ever lose them, I will remain your wife no longer and will return to heaven. Moreover, I shall live only on clarified butter.‖
Pururava agreed to these rather strange conditions and the two were married. They lived happily for sixty-four years.
But the gandharvas who were in heaven felt despondent. Heaven seemed to be a dismal place in Urvashi‘s absence. They therefore hatched a conspiracy to get her back. On an appropriate occasion, a gandharva named Vishvavasu stole the two sheep. As soon as this happened, Urvashi vanished and returned to heaven.
Pururava pursued Vishvavasu and managed to retrieve the sheep, but by then, Urvashi ahd disappeared. The miserable king searched throughout the world for her. But in vain. Eventually, Pururava came across Urvashi near a pond in Kurukshetra.
―Why have you forsaken me?‖ asked Pururava. ―You are my wife. Come and live with me.‖
―I was your wife,‖ replied Urvashi. ―I no longer am, since the condition was violated. However, I agree to spend a day with you.‖
When one year had passed, Urvashi returned to Pururava and presented him with the son she had borne him. She spent a day with him and vanished again. This happened several times and, in this fashion, Urvashi bore Pururava six sons. They were named Ayu, Amavasu, Vishvayu, Shatayu, Gatayu and Dridayu.