Heimskringla Grant Age

The son of Jǫrundr, who was king over the Svíar after his father, was called
Aun or Áni. He was a wise man and held many sacrifices. He was no warrior
but stayed in his own territories. At the time when those kings who have
been told about above were at Uppsalir, there was ruling Denmark first Danr inn
mikilláti—he lived to a great age; then his son, Fróði inn mikilláti (the Haughty)
or inn friðsami (the Peaceful), then his sons, Hálfdan and Friðleifr. They were
great warriors. Hálfdan was the elder and took the lead in everything. He went
with his army to Svíþjóð against King Aun, and they had some battles, and
Hálfdan always won, and in the end King Aun fled to Vestra-Gautland. He had
then been king over Uppsalir for twenty years. He stayed for a further twenty
years in Gautland while King Hálfdan was at Uppsalir. King Hálfdan died of
sickness at Uppsalir, and he is buried there. After that King Aun returned to
Uppsalir. He was then sixty years of age. Then he held a great sacrifice for
length of life, and offered up his son to Óðinn, and he was sacrificed. Then
King Aun received from Óðinn the answer that he would live for a further
sixty years. Aun was king at Uppsalir for another twenty years. Then Áli inn
frœkni (the Valiant), son of Friðleifr, came with his army to Svíþjóð against
King Aun, and they fought battles, and Áli always won. Then King Aun fled
his kingdom a second time and went to Vestra-Gautland. Áli was king at
Uppsalir for twenty years until Starkaðr inn gamli killed him. After the fall of
Áli, King Aun went back to Uppsalir and then ruled the kingdom for another
twenty years. Then he held a great sacrifice and offered up his second son. Then
Óðinn told him that he would live forever as long as he sacrificed a son of his
to Óðinn every ten years, and also that he must give a name to some district
in his land based on the number of his sons he had sacrificed to Óðinn. And
when he had sacrificed seven of his sons, he lived for ten years without being
able to walk. Then he was carried on a chair. Then he sacrificed his eighth
son, and lived for another ten years, lying bed-ridden. Then he sacrificed his
ninth son and lived a further ten years. He had to drink from a horn like a
baby. Then Aun had one son left, and he was going to sacrifice him, and was
going to give Óðinn Uppsalir and the districts belonging to it, and have it
called Tíundaland (‘Tenth land’). The Svíar stopped him doing that, and no
sacrifice was held. Then King Aun died, and he is buried at Uppsalir. Since
then it has been called Ánasótt ‘Áni’s sickness’ (properly ‘old-age sickness’)
if a man dies painlessly of old age. So says Þjóðólfr:

18. Long ago
it was old age
Aun had to face
at Uppsalir,
clinging to life,
on baby food
he had to subsist
a second time.
And to himself
he turned the thinner
end of the
ox’s sword
when, lying, the killer
of kindred drank
from the tip of the yoke-
reindeer’s weapon.
The herd-sword
the hoary one,
the eastern king,
could not hold up.


- Heimskringla, Ynglinga Saga, Chapter 25