And the LORD said to Moses is an important break from the preceding verses, for it marks a transition in the basic pattern of the plague stories from part (a) to part (c). (See the pattern of the plagues, as listed on page 162.) We may assume, then, that the warning to the Pharaoh (part b) was delivered by Moses between verses 4 and 5. This is now a command to initiate the second plague.

Say to Aaron introduces the words from the LORD that Moses is to say to Aaron. Stretch out your hand refers to Aaron’s hand, and with your rod refers to Aaron’s “staff” (New Revised Standard Version), or “walking stick” (Good News Translation). This is the same action that was commanded of Aaron in 7.19, although the wording is slightly different. For rivers, canals, and pools, see the discussion at 7.19a. (Note that the pronoun “their” is not used, and “waters” and “ponds” are not mentioned.) The Hebrew word for pools in 8.5 is the same word that Revised Standard Version renders as “ponds” in 7.19.

Cause frogs to come upon the land of Egypt is a command still addressed to Aaron. His action will activate the plague. Good News Translation adds some information here by borrowing from the next verse: “and cover the land of Egypt.”

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 .