The Epic of Gilgamesh:

The Return

After the death of his best friend Enkidu, Gilgamesh begins a search for everlasting life so no one would mourn his death like he mourned Eniku. He traveled far distances to find this.

He traveled over the wilderness...

He wandered over the grasslands...

Then, Gilgamesh found Utnapishtim. Utnapishtim told Gilgamesh,

"Prevail against sleep, immortal, for six days and seven nights. You will then be gifted with eternal life."

Gilgamesh began to grow sleepy, and a deep sleep drifted upon him.

Utnapishtim explained to his wife that Gilgamesh will try to lie to her and say he was not asleep. For this, she will mark the wall and make a loaf of bread for each day Gilgamesh sleeps.

On the morning of the seventh day, Gilgamesh awoke to see the first loaf of bread was hard, the second loaf was like leather, the third was soggy, the crust on the fourth had mild, the fifth was mildewed, the sixth was fresh, and the seventh was still in the oven.