Brahmā said:
1. The holy centre named Purūravas destroys all sins even on being remembered. Why not on being visited? Those who are conversant with the Vedas know it.
2. King Purūravas went to the abode of Brahmā. There, by chance he saw the divine river Sarasvati laughing by the side of Brahma. On seeing her richly endowed with beauty the king asked Urvašhī:
The King said:
3. Who is this beautiful saintly lady near Brahmä? She is the most excellent lady among all ladies (assembled here). She (seems to) illuminate this assembly.
Brahmā said:
4. Urvasī said to the king: "This is the splendid divine river Sarasvati, the daughter of Brahma. She comes here daily and gocs back.”
On hearing it the king was surprised (and he said), "Bring her near me
Brahma said:
5-9. Urvašhīsaid again to the king who used to distribute plenty of monetary gifts.
Urvašhīsaid:
I shall mention everything to her and fetch her.
Brahma said:
Then out of pleasure the king sent Urvaśī there. Urvašhīthen went and repeated the words of the king. Sarasvati agreed to what was mentioned by Urvasī. She promised saying "So be it" and went to the place where Purūravas was staying. He indulged in sexual dalliance on the banks of Sarasvati for many years. Sarasvan was born as (her) son and his (Sarasvan's) son was Bruhadratha.
10-12. I observed Sarasvati going everyday to the abode of the king. I saw Sarasvăn (her son). I saw evidences of similar activities with regard to other persons also. So I cursed her, "Be Mahanadi." Afraid of my curse Vägisā (Sarasvati) went to the divine river Gautami, who is the holy mother sanctifying the whole world, who was born of Kamandalu (water pot), who is the suppressor of the three distresses and who is the bestower of pleasures here and hereafter.
13-16. After going to Gautami, the divine river, she recounted (the story of) my curse from the beginning. Ganga said to me: "It behoves you to make her free from the effects of the curse. It is not proper on your part to have cursed Sarasvati. This is the nature of women because youthful women desire men. O Brahma, all young women are naturally unsteady. O lotus-seated lord, you are the creator of the Universe. How is it, that you do not know this? Whom does not cupid deceive naturally?”
Then I withdrew the curse and said "Sarasvati shall be visible too."
17-20. Due to that curse the river Sarasvati is both visible and invisible in the mortal world.
Purūravas, the most excellent and virtuous king, went to the place where the divine river (Sarasvati), agitated due to the curse, joined Ganga. He performed penance and propitiated lord Siddheśvara. He acquired all cherished desires by the favour of Ganga. Thenceforth that holy centre is called Purūravas. It is also called Sarasvatisangama and Brahmatirutha. The lord there is Siddhesvara and the holy center bestows all cherished tủings.
Summary of chapter 31 of the Brahma Purana is as follows:
The confluence of the sacred river Sarasvatī with Gautamī is described and its extraordinary sanctity extolled. At this meeting point of two of the holiest rivers of Bhārata, the cumulative merits of both rivers combine, and the devotee who bathes here receives the spiritual benefits of pilgrimage to all the tīrthas of both rivers simultaneously.