The magicians are the same “magicians of Egypt” mentioned in 7.11 and 7.22. Here again, they did the same by their secret arts. (See the translation and comments there.) Brought frogs is literally “they caused to come up frogs,” as in verse 5. Upon is literally “up upon.” Good News Translation adds the word “also,” since they did the same thing, meaning they also caused the frogs to “come up on the land” from the water.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .