Why are the deeds of sigemund mentioned with beowulfs defeat of grendel?

Sigemund's story is mentioned in Beowulf to draw a parallel between the two heroes. Both Sigemund and Beowulf display courage, strength, and glory in their respective exploits, illustrating the heroic code of the time. Sigemund's story serves as a foil to Beowulf's own achievements, highlighting the legacy and prowess of these great warriors.