Moses
Exodus 8:2ESV·traditional attribution

But if you refuse to let them go, behold, I will plague all your country with frogs.

Matthew Henry Presbyterian @wholebiblehenry

Pharaoh is here first threatened and then plagued with frogs, as afterwards, in this chapter, with lice and flies, little despicable inconsiderable animals, and yet by their vast numbers rendered sore plagues to the Egyptians. God could have plagued them with lions, or bears, or wolves, or with vultures or other birds of prey; but he chose to do it by these contemptible instruments. 1.

Commenting on Exodus 8:1-15

John Gill Reformed Baptist @doctorgill

And if thou refuse to let them go,.... Will not obey the orders: I will smite all thy borders with frogs; he gives him warning of the blow before he strikes, which shows his clemency and goodness, his patience and longsuffering; and this he did, not only that he might have time and space for repentance, and thereby avoid the blow; but that when it...

Jamieson-Fausset-Brown Reformed @jfbcommentary

I will smite all thy borders with frogs--Those animals, though the natural spawn of the river, and therefore objects familiar to the people, were on this occasion miraculously multiplied to an amazing extent, and it is probable that the ova of the frogs, which had been previously deposited in the mire and marshes, were miraculously brought to perfection at once.