Stanza 16: Hymir is referred to as the "hoary friend of Hrungnir" after seeing how much Þórr has eaten.
It seemed to the hoary friend of Hrungnir
that Hlórriði’s meal was, well, large enough:
‘Tomorrow evening, we three will have to live
on food caught by fishing!’
Stanza 14-15: Hárbarðr (Odin in disguise) taunts Þórr, claiming to be a tougher opponent than the giant Hrungnir, whom Þórr had killed. In response, Þórr recalls his famous duel with the "stout-hearted giant whose head was made of stone."
Hárbarðr said:
14.‘Here I’ll stand and here I’ll await you;
you’ve not found a harder man since Hrungnir’s death!’
Þórr said:
15.‘Now you want to talk of the time when Hrungnir and I had dealings,
that stout-hearted giant whose head was made of stone;
even so, I made him fall and sink before me!
What were you doing meanwhile, Hárbarðr?’
Stanza 61: Þórr threatens Loki with his hammer Mjǫllnir, calling it "Hrungnir's slayer" to emphasize its deadly power.
‘Silence, perverted creature! My power-hammer,
Mjǫllnir, shall deprive you of speech;
with my right hand I’ll strike you with Hrungnir’s slayer,
so that all your bones will be broken!’
Stanza 63: Þórr repeats his threat, again referring to Mjǫllnir as "Hrungnir's slayer" before declaring he will send Loki to Hel.
‘Silence, perverted creature! My power-hammer,
Mjǫllnir, shall deprive you of speech;
Hrungnir’s slayer will send you to Hel,
down below corpse-gates!’
Chapter 4(p. 73): In a verse by the skald Bragi, Thor's hammer Mjöllnir is given the kenning (a poetic name) "Hrungnir’s skull-splitter."
And the ugly ring [serpent] of the side-oared ship’s road [sea] stared up spitefully at Hrungnir’s skull-splitter.
Chapter 17(p. 77): The main narrative of the duel begins. Odin, riding Sleipnir, encounters Hrungnir and they wager on which of their horses is superior. This chase leads to Hrungnir recklessly entering Asgard.
...Odin rode Sleipnir into Giantland and arrived at a giant’s called Hrungnir. Then Hrungnir asked what sort of person this was with the golden helmet riding sky and sea, and said he had a marvellously good horse.
Chapter 17(p. 78): After getting drunk in the gods' hall, Hrungnir becomes boastful and threatening. Thor arrives and challenges him. Hrungnir agrees to a formal duel, and the text describes his famous stone heart, head, and shield.
Then Thor said that Hrungnir was going to regret that invitation before he got out. Hrungnir said it would be no honour to Asa-Thor to kill him when he was unarmed, whereas it would be a greater proof of his valour if he dared to fight with him on the frontier at Griotunagardar.
Chapter 17(p. 79): The duel is described in detail. Thor's hammer shatters Hrungnir's whetstone and then his skull. The giant falls dead, trapping Thor beneath his leg.
...the hammer Miollnir hit the middle of Hrungnir’s head and shattered his skull into small fragments...
‘And I have decided,’ he said, ‘to give you the horse Gullfaxi, which used to be Hrungnir’s.’
Chapter 17(p. 80): A long passage from the poem Haustlöng is quoted, which poetically recounts the story of Thor's encounter with the giant.
...when the goats drew the temple-power [Thor] of the easy-chariot forward to the encounter with Hrungnir.
Baldr’s brother [Thor] did not spare there the greedy enemy of men [Hrungnir].