Poetic Edda/Dráp Niflunga
Gunnar and Hogni then took all the gold, Fáfnir's heritage. Dissension prevailed afterwards between the Gjukungs and Atli. He charged them with, being the cause of Brynhild's death. By way of reconciliation, it was agreed that they should give him Gudrun in marriage, to whom they administered an oblivious potion, before she would consent to espouse Atli. Atli had two sons, Erp and Eitil, but Svanhild was the daughter of Sigurd and Gudrun. King Atli invited Gunnar and Hogni to his residence, and sent to them Vinge, or Knefrad. Gudrun was aware of treachery, and sent them word in runes not to come; and to Hogni, as a token, she sent the ring Andvaranát, in which she had tied some wolf's hair.
Gunnar had sought the hand of Oddrun, Atli's sister, but did not obtain it. He then married Glaumvor, and Hogni took Kostbera to wife. Their sons were Solar, Snevar, and Gjuki. When the Gjukungs came to Atli, Gudrun besought his sons to intercede for their lives, but they would not. The heart of Hogni was cut out, and Gunnar was cast into the Snakepit. He struck his harp and lulled the serpents, but a woman cut him to the liver.