John Gill Commentary Exodus 10:22

"And Moses stretched forth his hand toward heaven; and there was a thick darkness in all the land of Egypt three days;" — Exodus 10:22 (ASV)

And Moses stretched forth his hand toward heaven, and there was a thick darkness over all the land of Egypt three days. The eleventh, twelfth, and thirteenth days of the month Abib; with this compare the fifth vial, (Revelation 16:10).