Mbh 1.111.4a

“Vaisampayana continued, ‘Vivaswat thus spoke unto her many things with a view to allay her fears, but, O Bharata, the amiable maiden, from modesty and fear of her relatives, consented not to grant his request. And, O bull of Bharata’s race, Arka addressed her again and said, ‘O princess, for my sake, it shall not be sinful for thee to grant my wish.’ Thus speaking unto the daughter of Kuntibhoja, the illustrious Tapana--the illuminator of the universe--gratified his wish. And of this connection there was immediately born a son known all over the world as Karna accountred with natural armour and with face brightened by ear-rings. And the heroic Karna was the first of all wielders of weapons, blessed with good fortune, and endued with the beauty of a celestial child. And after the birth of this child, the illustrious Tapana granted unto Pritha her maidenhood and ascended to heaven. And the princess of the Vrishni race beholding with sorrow that son born of her, reflected intently upon what was then the best for her to do. And from fear of her relatives she resolved to conceal that evidence of her folly. And she cast her offspring endued with great physical strength into the water. Then the well-known husband of Radha, of the Suta caste, took up the child thus cast into the water, and he and his wife brought him up as their own son. And Radha and her husband bestowed on him the name of Vasusena (born with wealth) because he was born with a natural armour and ear-rings. And endued as he was born with great strength, as he grew up, he became skilled in all weapons. Possessed of great energy, he used to adore the sun until his back was heated by his rays (i.e., from dawn to midday), and during the hours of worship, there was nothing on earth that the heroic and intelligent Vasusena would not give unto the Brahmanas.