What scriptures describe the story of the frog princess?

Question

As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school. But there are five other Astika or orthodox schools of Hindu philosophy: Purva Mimamsa, Samkhya, Yoga, Vaisheshika, and Nyaya. My question is about the Samkhya school, founded by the sage Kapila. Now in Adhyaya 4 of Kapila's Samkhya Sutras, one of the defining texts of the Samkhya school, Kapila discusses various scriptural stories which illustrate different Samkhya teachings. In particular, here's what he says in Adhyaya 4 Sutra 16:

tadvismaraṇe'pi bhekīvat

In the forgetting also of the rules (there is the same harm), as (in the story of) the she-frog.

Here's how Aniruddha interprets this Sutra in his commentary on the Samkhya Sutras:

The author tells us that by reason of the forgetting of the knowledge of the Principles, pain necessarily takes place. A certain king, going out on a hunting excursion, saw a beautiful maid in the woods. He asked her, "Who are you?" "I am a king's daughter," replied she. The king said, "Marry me." "Very well," said she, "but make this rule that water must not be shown to me by you." "Let it be so," - so saying, he took her hand. In this manner, as time went on, one day, she, being fatigued with sport, asked the king "Where can I get water from?" The king, too, forgetting his promise, through haste, showed her water. And she, who was the daughter of the king of frogs, was, through touch of water, transformed as a she-frog. The king, on the other hand, searching for her by means of nets, etc. and, not regaining her, experienced much pain. Therefore, interruption of the cultivation of the Principles should not be made.

My question is, what scriptures describe this story of a king who fell in love with a frog princess?

This story is interesting for two reasons. First of all, it's reminiscent of the story of Shantanu and Ganga, in that a wife places a condition that the husband breaks. Second of all, it reminds me of the European story of the Frog Prince. In fact, it's kind of the mirror image of that story. In the Frog Prince, a princess keeps a promise to a male frog, and thereby it turns into a human. In this story, a king breaks a promise to a female human, and thereby she turns into a frog.

Answer 1

I found the story in this chapter of the Vana Parva of the Mahabharata. Markandeya tells the story to the Pandavas to illustrate the power of Brahmanas. The king in the story is the ancient solar dynasty king Parikshit, not to be confused with Arjuna's grandson Parikshit who belonged to the lunar dynasty. Here is the part of Markandeya's story that is summarized by Aniruddha's quote above:

There was a king, by name Parikshit in Ayodhya and belonging to the race of Ikshvaku. And once upon a time Parikshit went a-hunting.... And the king soon beheld a maiden of great beauty gathering flowers singing all the while, and the maiden soon came before the king, and the king thereupon asked her, 'Blessed one, who art thou and whose?' And she replied, 'I am a maiden.' And the king said, 'I ask thee to be mine.' And the maiden answered, 'Give me a pledge, for then only I can be thine, else not.' And the king then asked about the pledge and the girl answered. 'Thou wilt never make me cast my eyes on water', and the king saying, 'So be it,' married her[.]... [A]nd the king sported with her in that delightful forest, and afflicted with hunger and thirst and fatigued and spent, the king beheld a bower of Madhavi creepers 1 and entering that bower with his dear one, the king beheld a tank full of water that was transparent and bright as nectar, and beholding that tank, the king sat on its bank with her and the king told his adorable wife, 'Cheerfully do thou plunge into this water!' And she, hearing those words plunged into the tank. But having plunged into the water she appeared not above the surface, and as the king searched, he failed to discover any trace of her. And the king ordered the waters of the tank to be baled out, and thereupon he beheld a frog sitting at the mouth of a hole[.]

But Markandeya continues the story far beyond this. Parikshit, enraged by his wife turning into a frog, decides to exterminate the entire race of frogs, just as Arjuna's great-grandson Janamejaya tried to exterminate the race of Nagas and Vyasa's father Parashara tried to exterminate the race of Rakshasas. Then Ayu, king of frogs, comes to Parikshit and he explains that it was his daughter Shushobana who had married Parikshit and that she had tricked other kings in the same manner. Parikshit agrees to stop killing frogs in exchange for getting Shushobana back. But before Ayu gives Shushobana back, he punishes his daughter for her trickery by putting a curse on her that her sons will be disrespectful to Brahmanas. Then Parikshit and Shushobana are reunited and have three sons named Sala, Dala, and Vala. Eventually Parikshit retires to the forest and Sala becomes king, and as prophesied he is disrespectful to Brahmanas: he borrows two great horses from the sage Vamadeva and refuses to give them back. So Vamadeva creates four Rakshasas who kill Sala. Then Dala becomes king, and he tries to kill Vamadeva with an arrow, but Vamadeva makes the arrow kill Dala's son. Then Dala takes another arrow to kill Vamadeva, but Vamadeva prevents Dala from even firing it. Finally Dala's wife convinces Dala to stop trying to kill Vamadeva, and Vamadeva becomes Dala's priest and Dala finally returns Vamdeva's horses.

So bottom line, don't disrespect Brahmanas!