Garuda is on his way to get amrita for his stepbrothers, the serpents.
That’s what they asked for to relieve him and his mother from slavery.
On the way, he ate thousands of cruel nishadas on an island.
This is what his mother had asked to do if he feels hungry.
Then he happened to meet his father Kashyapa Prajapati on the way.
Kashyapa inquired about the well-being of him, his brother, and his mother.
Garuda said we are all good.
Then Kashyapa asked are you getting enough food in Manushyaloka?
No, that's a problem.
I just ate thousands of nishadas and still, I am hungry.
Please show me something else that I can eat and satisfy my hunger.
I need to go and get the amrita.
Kashyapa thought getting amrita from devas is not going to be easy. There is going to be a big fight.
Garuda needs to be fit for that fight.
Kashyapa said, see this lake here.
There is an elephant and a tortoise in this lake.
They are huge in size.
The height of that elephant is six yojanas.
His length is 12 yojanas.
The tortoise is 3 yojanas in height and ten yojanas in diameter.
You can have them.
Then Kashyapa told Garuda the background of the elephant and tortoise.
They were brothers, both tapaswis.
The elder brother's name was Vibhavasu and the younger one Suprateeka.
They were together.
Their wealth and properties were together.
Suprateeka wanted partition.
He kept on asking and Vibhavasu kept on delaying.
Once,Vibhavasu told him: it is not good that brothers partition their properties.
That is not a solution.
After partition, they will start fighting.
Each one will think I didn't get my proper share and start fighting.
Greed will come in.
Once enemies realize that the brothers have separated, they will come in disguised as friends, instigate them, and make them fight more causing destruction of the family.
Then,there are those trouble makers who poke their nose into everything.
They will also join sides, corrupt the minds and watch the fun.
So partition is not good.
Even shastra says that the younger brother should look upon the elder brother as father and the elder brother should look upon the younger brother as a son.
You don't seem to be understanding all these.
You are obsessed with partition.
You have become filled with tamoguna.
Go and take birth as an elephant.
Vibhavasu cursed Suprateeka.
Suprateeka also cursed Vibhavasu: you become a tortoise.
But even after that, they kept on fighting.
In the lake.
The elephant would come to the shore of the lake.
Seeing that, the tortoise would come up.
The elephant would jump into the lake and then they both fight.
Big ruckus.
They wanted to kill each other.
Kashyapa said: go and eat them both, then go get amrita.
Kashyapa wished Garuda success by saying mangala vakyas.
When Garuda went near the lake he saw the elephant and tortoise.
He held the elephant with one of his claws and the tortoise with the other.
Now you can imagine garudas size.
Then he flew up and went to अलम्बतीर्थ.
There was a huge banyan tree there.
See this branch of mine, this is 100 yojanas long you can sit on that and consume your food.
Garuda sat on the branch and it broke.
But Garuda held it and stopped it from falling down.