Pyramid Texts- Tomb of Pepi II.

Notice how the word 'Amen' is used: For the Snake God Amen.

http://one-faith-of-god.org/old_testament/sources/amen/amen_0040.htm

(1539 - 1540 BCE)

1.
To say : This going forth from your house, O Osiris, this Pharaoh Pepi,

2.
is the going forth of Horus seeking You, O Osiris, this Pharaoh Pepi.

3.
Your porters hasten, your couriers run, your heralds hurry .

4.
They announce to Re that You have come, O this Pharaoh Pepi,

5.
as the Son of God upon the throne of Amen.

6.
your shadow.