Because of the frogs— Houbigant renders this, respecting that which be had promised Pharaoh touching the frogs. The phrase עלאּדבר ol-debar, which we render, properly enough, because of, is, literally, touching the affair.
Related Commentaries of Exodus 8:12
Exodus 8:12
12 And Moses and Aaron went out from Pharaoh: and Moses cried unto the LORD because of the frogs which he had brought against Pharaoh.