Mbh 9.48.1b

Everything rests on penances. All those regions of blessedness, O thou of beautiful face, that belong to the gods can be obtained by penances. Penances are the root of great happiness. Those men that cast off their bodies after having practised austere penances, obtain the status of gods, O auspicious one! Bear in mind these words of mine! Do thou now, O blessed damsel, boil these five jujubes, O thou of excellent vows!' Having said these words, the adorable slayer of Vala went away, taking leave, to mentally recite certain mantras at an excellent tirtha not far from that hermitage. That tirtha came to be known in the three worlds after the name of Indra, O giver of honours! Indeed, it was for the purpose of testing the damsel's devotion that the Lord of the celestials acted in that way for obstructing the boiling of the jujubes. The damsel, O king, having cleansed herself, began her task; restraining speech and with attention fixed on it, she sat to her task without feeling any fatigue. Even thus that damsel of high vows, O tiger among kings, began to boil those jujubes. As she sat employed in her task, O bull among men, day was about to wane, but yet those jujubes showed no signs of having been softened. The fuel she had there was all consumed. Seeing the fire about to die away owing to want of fuel, she began to burn her own limbs. The beautiful maiden first thrust her feet into the fire. The sinless damsel sat still while her feet began to be consumed. The faultless girl did not at all mind her burning feet. Difficult of accomplishment, she did it from desire of doing good to the Rishi (that had been her guest). Her face did not at all change under that painful process, nor did she feel any cheerlessness on that account. Having thrust her limbs into the fire, she felt as much joy as if she had dipped them into cool water. The words of the Rishi, 'Cook these jujubes well' were borne in her mind, O Bharata!