Mbh 12.2.2b

' When Drona had answered thus, Karna, having worshipped him, obtained his leave, and proceeded without delay to Rama then residing on the Mahendra mountains. Approaching Rama, he bent his head unto him and said, 'I am a Brahmana of Bhrigu's race.' This procured honour for him. With this knowledge about his birth and family, Rama received him kindly and said, 'Thou art welcome!' at which Karna became highly glad. While residing on the Mahendra mountains that resembled heaven itself, Karna met and mixed with many Gandharvas, Yakshas, and gods. Residing there he acquired all the weapons duly, and became a great favourite of the gods, the Gandharvas, and the Rakshasas. One day he roved on the sea-coast by the side of that asylum. Indeed, Surya's son, armed with bow and sword, wandered alone, While thus employed, O Partha, he inadvertently slew, without witting it, the Homa cow of a certain utterer of Brahma who daily performed his Agnihotra rite. Knowing that he had perpetrated that act from inadvertence, he informed the Brahmana of it. Indeed Karna, for the object of gratifying the owner, repeatedly said, 'O holy one, I have killed this thy cow without willing it. Forgive me the act!' Filled with wrath, the Brahmana, rebuking him, said these words, 'O thou of wicked conduct, thou deservest to be killed. Let the fruit of this act be thine, O thou of wicked soul. While fighting him, O wretch whom thou always challengest, and for whose sake thou strivest so much every day, the earth shall swallow the wheel of thy car! And while the wheel of thy car shall thus be swallowed up by the earth, thy foe, putting forth his prowess, will cut off thy head, thyself being stupefied the while! Leave me, O vile man! As thou hast heedlessly slain this my cow, even so wilt thy foe cut off thy head while thou shalt be heedless!' Though cursed, Karna still sought to gratify that foremost of Brahmanas by offering him kine and wealth and gems.