What is the explanation of His saying, the Exalted: "And you make your provision that you deny."

Provision here means gratitude.

"And you make your provision that you deny" means you make your gratitude; because He mentioned the blessings.

The Exalted: Have you seen what you sow? Have you seen what you emit? Have you seen the water you drink? Have you seen the fire you kindle? He mentioned these blessings.

Then He said: "And you make your provision that you deny," instead of thanking Allah, you deny.

This is how Allah, the Blessed and Exalted, recompenses. So here, you make your provision, meaning your gratitude.

That you deny.