Moses
Exodus 8:20ESV·traditional attribution

Then the LORD said to Moses, “Rise up early in the morning and present yourself to Pharaoh, as he goes out to the water, and say to him, ‘Thus says the LORD, “Let my people go, that they may serve me.

John Calvin Reformed @genevareformer

20. And the Lord said unto Moses, Rise up early. As Pharaoh advances in daring rashness, so does God on the other hand proceed to restrain his impetuosity by opposing impediments. This is what the wicked at length obtain by long and multiplied contention, that having received many wounds they perish by various torments.

Matthew Henry Presbyterian @wholebiblehenry

Here is the story of the plague of flies, in which we are told, I. How it was threatened, like that of frogs, before it was inflicted. Moses is directed (Exo 8:20) to rise early in the morning, to meet Pharaoh when he came forth to the water, and there to repeat his demands. Note, 1.

Commenting on Exodus 8:20-32

John Gill Reformed Baptist @doctorgill

Else, if thou wilt not let my people go,.... But remainest obstinate and inflexible: behold, I will send swarms of flies upon thee; the word used is generally thought to signify a "mixture", and is interpreted by many a mixture of various creatures; the Targum of Jonathan paraphrases it a mixture of wild beasts, and so Josephus (k) understands it of all sorts of beasts...