Entreat the LORD means “Pray to the LORD” (Good News Translation), or “Plead with Yahweh.” It is addressed to both Moses and Aaron. The same request is found in 8.8; 8.28; and 10.17. For is literally “and,” but it introduces the reason why Moses and Aaron are requested to pray. There has been enough really means “We have had enough” (Good News Translation), or even “We can’t stand [or, endure] any more” (similarly Contemporary English Version).
This thunder is literally “thunder [sounds] of God.” New Revised Standard Version has changed Revised Standard Version to “God’s thunder,” as in New American Standard Bible, New Jewish Publication Society’s Tanakh, New American Bible, and others. But it should be noted that the word for God is ʾelohim, not Yahweh (the LORD), to whom the king has asked them to pray. This change in the same sentence may be significant, as Moses’ reply in 9.30 suggests. But both Revised Standard Version and Good News Translation conceal this change of terms by translating ʾelohim with the demonstrative “this.” (So also New English Bible, but New International Version omits it altogether.) But to do so suggests that the king is now recognizing Yahweh as God, since he has just asked for prayer to Yahweh, who has sent the storm.
Some translations therefore have interpreted this as an example of the “ʾelohim superlative,” where ʾelohim is used as an adjective to express something supernatural or extraordinary, that is “exceedingly great.” (See the passages where ʾelohim is used as that kind of an adjective; for example, Gen 30.8 “mighty wrestlings,” 1Sam 14.15 “a very great panic,” Jonah 3.3 “an exceedingly great city,” etc.) This is why King James Version and American Standard Version have “mighty thunderings,” and Translator’s Old Testament has “terrible thunder.”
The translator therefore must choose from three possible uses of the word ʾelohim: (a) as a possessive (“God’s thunder,” “thunder of God,” or “the roaring of the sky caused by God”), (b) as an adjective (“mighty thunderings,” “terrible thunder,” or “the sky’s great roaring noise”), or (c) as a demonstrative (this thunder). Some translators may want to follow (a) in order to suggest that the king is still making a distinction between ʾelohim, the God of the thunder, and YHWH, the God of the Israelites. (In verse 20 Moses uses the expression YHWH ʾelohim. See the comment there.) It is probably better to follow (b) in this case, but a footnote giving the literal meaning is recommended. In some languages it will be more natural style to reorder the first two sentences and translate, for example, “We can’t stand this terrible thunder or the hail anymore. So please plead with Yahweh to make them stop.”
I will let … go is one word in the Hebrew, followed by the pronoun you in the plural, referring to all the Israelites. The form of the verb indicates strong determination on the Pharaoh’s part, so Good News Translation has “I promise” (so also Jerusalem Bible and New Jerusalem Bible). But the conjunction waw (“and”), which neither Revised Standard Version nor Good News Translation translate, is attached to the verb (literally “and I will send out”). New American Bible and Translator’s Old Testament in this case translate the waw as “Then.” This suggests that the king fully intends to release them when the plague is lifted. Therefore his “promise” should not be thought of as an unconditional vow, as when a person takes an oath. The king obviously expects that the LORD will stop the thunder and hail when Moses prays.
You shall stay no longer uses an emphatic form of the verb that also suggests the king’s determination. But this is not a command; rather it is a concession. That is, the king will now permit them to leave. So Good News Translation has “You don’t have to stay in Egypt any longer.”
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 .