Origin of repeating words for emphasis or clarification

It’s literally ancient.

From the Old Testament book of Isaiah: “Holy, holy, holy is the LORD God Almighty.”

Missed the edit window, but here is the exact quote:

*Above him were seraphs, each with six wings: With two wings they covered their faces, with two they covered their feet, and with two they were flying. And they were calling to one another:
Holy, holy, holy is the LORD Almighty;
the whole earth is full of his glory.” *

  • Isaiah 6:2-3