Fafnir his foster-son Sigurd to kill the dragon. Regin instructed Sigurd to dig a pit in which he could lie in wait under the trail Fáfnir used to get to a stream and there plunge his sword, Gram, into Fafnir's heart as he crawls over the pit to the water. Regin then ran away in fear, leaving Sigurd to the task. As Sigurd dug, Odin appeared in the form of an old man with a long beard, advising the warrior to dig more trenches for the blood of Fafnir to run into, presumably so that Sigurd does not drown in the
Fafnir while cooking the heart, gained knowledge of the speech of birds and learned of Regin's impending attack from the Oðinnic (of Odin) birds' discussion and killed Regin by cutting off his head with Gram. Sigurd then ate some of Fafnir's heart and kept the remainder, which would later be given to Gudrun after their marriage. Some versions are more specific about Fáfnir's treasure hoard, mentioning the swords Ridill and Hrotti, the helm of terror and a golden coat of chainmail. Fafnir appears – as "Fafner" – in Richard Wagner's epic opera cycle "Der Ring des Nibelungen" (1848–1874), although he began