{{The Nibelungenlied}} but in it's prose form.
https://www.amazon.co.uk/Nibelungenlied-Penguin-Classics-Hatto/dp/0140441379/ref=sr_1_2?crid=13OPV4MTYPQF7&dchild=1&keywords=nibelungenlied&qid=1627595771&sprefix=nibelungen%2Caps%2C158&sr=8-2
I was so hooked when I read it and I need to re-read it again! It's an ancient Germanic saga.