Mbh 1.133.3a

“Drona had thus lived privately for some time in the house of Kripa when one day the heroic princes, all in a company, came out of Hastinapura. And coming out of the city, they began to play with a ball and roam about in gladness of heart. And it so happened that the ball with which they had been playing fell into a well. And thereupon the princes strove their best to recover it from the well. But all the efforts the princes made to recover it proved futile. They then began to eye one another bashfully, and not knowing how to recover it, their anxiety became great. Just at this time they beheld a Brahmana near enough unto them, of darkish hue, decrepit and lean, sanctified by the performance of the Agnihotra and who had finished his daily rites of worship. And beholding that illustrious Brahmana, the princes who had despaired of success surrounded him immediately. Drona (for that Brahmana was no other), seeing the princes unsuccessful, and conscious of his own skill, smiled a little, and addressing them said, ‘Shame on your Kshatriya might, and shame also on your skill in arms! You have been born in the race of Bharata! How is it that ye cannot recover the ball (from the bottom of this well)? If ye promise me a dinner today, I will, with these blades of grass, bring up not only the ball ye have lost but this ring also that I now throw down!’ Thus saying, Drona that oppressor of foes, taking off his ring, threw it down into the dry well. Then Yudhishthira, the son of Kunti, addressing Drona, said, ‘O Brahmana (thou askest for a trifle)! Do thou, with Kripa’s permission, obtain of us that which would last thee for life!’ Thus addressed, Drona with smiles replied unto the Bharata princes, saying, ‘This handful of long grass I would invest, by my mantras, with the virtue of weapons. Behold these blades possess virtues that other weapons, have not!