Over Edom I will cast My SHOE

[TonyChanYT]

New King James Version Psalm 60:

8 Moab is My washpot; Over Edom I will cast My shoe; Philistia, shout in triumph because of Me.”

What was the imagery of casting one's shoe?

Ellicott might be helpful:

Of the "shoe," as a figure of what is vilest and most common, Dr. J. G. Wetzstein quotes many Arabic proverbs. A covering for the feet would naturally draw to it such associations.

Arabs associated shoes with foul objects.

But the custom which Israel brought from Egypt (Exodus 3:3), of dropping the sandals outside the door of a temple, and even of an ordinary house, must have served still more to fasten on that article of dress, ideas of vileness and profanation.

Egyptians associated shoes with religious uncleanness.

Even today, when you visit a Japanese home, you take off your street shoes at the entrance and exchange them for indoor slippers.

A similar idea was in (NIV) Psalm 108:

9 Moab is my washbasin, on Edom I toss my sandal; over Philistia I shout in triumph.”

It was a symbol of conquest. David conquered Edom in 2 Samuel 8:

14 He placed garrisons throughout Edom, and all the Edomites were subject to David. So the LORD made David victorious wherever he went.

Figuratively, the Edomites became David's servants and were responsible for cleaning his dirty sandal.