Mahabharata 1.121.8

1.121.8

bharadvājasakhā cāsītpṛṣato nāma pārthivaḥ |
tasyāpi drupado nāma tadā samabhavatsutaḥ || 8 ||

"There was a king named Prishata who was a great friend of Bharadwaja. About this time Prishata had a son born unto him, named Drupada. And that bull among Kshatriyas, viz., Drupada, the son of Prishata, used every day to come to the hermitage of Bharadwaja to play with Drona and study in his company. O monarch, when Prishata was dead, this Drupada of mighty arms became the king of the northern Panchalas. About this time the illustrious Bharadwaja also ascended to heaven. Drona continuing to reside in his father's hermitage devoted himself to ascetic austerities. Having become well-versed in the Vedas and their branches and having burnt also all his sins by asceticism, the celebrated Drona, obedient to the injunctions of his father and moved by the desire of offspring married Kripi, the daughter of Saradwat. And this woman, ever engaged in virtuous acts and the Agnihotra, and the austerest of penances, obtained a son named Aswatthaman. And as soon as Aswatthaman was born, he neighed like the (celestial) steed Ucchaihsravas. Hearing that cry, an invisible being in the skies said, 'The voice of this child hath, like the neighing of a horse, been audible all around. The child shall, therefore, be known by the name of Aswatthaman, (the horse-voiced). The son of Bharadwaja (Drona) was exceedingly glad at having obtained that child. Continuing to reside in that hermitage he devoted himself to the study of the science of arms.