Exodus 8:2
And if you refuse to let them go, behold, I will smite all your borders with frogs:
Exodus 7:14
And the LORD said unto Moses, Pharaoh's heart is hardened, he refuses to let the people go.
Exodus 9:2
For if you refuse to let them go, and will hold them still,
Psalm 78:45
He sent swarms of flies among them, which devoured them; and frogs, which destroyed them.
Psalm 105:30
Their land brought forth frogs in abundance, in the chambers of their kings.
Revelation 16:13-14
And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet.