This command says don’t take likely the purpose of your redemption. Don’t take for granted the reason of your initiation into eternal life by the sacrifice of HIS love.
So for Pharaoh, it was GOD's way of stretching his doubt to its limits; how far could his query of GOD go? However, Pharaoh did believe. In the moment of torment, in the evidence that these things were by the hand of GOD, Pharaoh believed.
And the authority of GOD is found in the minority of truth which is not the majority of sooth against the works of truth.