כלה Onkelos renders it by גמירא, taking כלה in sense of כליל entirely; i. e. he will send all of you away.

דבר נא SPEAK נא — The word נא is always an expression of entreaty. Here it means: I entreat you, admonish them about this which follows (impress this injunction upon them), so that righteous man, Abraham, may not say: the prophecy (Genesis 15:13) “they shall serve them, and they shall afflict them” He permitted to be fulfilled in them, but the promise (Genesis 15:14) “and afterwards they shall go forth with great substance” He did not bring to fulfilment for them (Berakhot 9a-b).

ויאמר משה כה אמר ה AND MOSES SAID, THUS SAITH THE LORD — Whilst he was still standing before Pharaoh this prophecy was spoken to him, because after he left him, he did not see his face again (Exodus Rabbah 18:1).

כחצות הלילה means, WHEN THE NIGHT IS DIVIDED (i. e., when midnight arrives). כחצות is an infinitive with prefix, of similar form to, (1 Kings 18:36) בעלות, “when went up” and (Psalms 124:3) “when their wrath was kindled (בחרות)”. This is its literal meaning which fits in with the sense, for חצות is not a noun, being another form of חֵצִי (when the meaning would be about midnight I will go out etc.”, for this does not fit in with the sense, since God would certainly have stated exactly when He would do this). But our Rabbis took it in this sense and explained it as meaning “about the middle of the night”, and they asserted that Moses said כחצות “about midnight”, which implies near to it — either just before it or just after it, and he did not say בחצות “at midnight” (as God had bidden him say) because he feared lest Pharaoh’s astrologers might make a mistake as regards the time when the slaughter of the firstborn actually took place, thinking that it was a little earlier or later than midnight, and would say, in consequence of this error, “Moses is a liar!” (cf. Berakhot 4a).

עד בכור השבי UNTO THE FIRSTBORN OF THE CAPTIVE (these words are used in 12:29 instead of עד בכור השפחה “unto the firstborn of the handmaid” in this verse) — Why were the captives smitten, for they had not enslaved the Israelites? In order that these might not say that their god had claimed satisfaction for the humiliation imposed upon them and had brought this punishment upon the Egyptians (cf. Mekhilta).

מבכור פרעה עד בכור השפחה FROM THE FIRSTBORN OF PHARAOH UNTO THE FIRSTBORN OF THE HANDMAID — All who were of less importance than the firstborn of Pharaoh and of more importance than the firstborn of the handmaid are included in this description. And why were the sons of the handmaids stricken? Because they, too, treated them (the Israelites) as slaves and rejoiced at their misery (Midrash Tanchuma, Bo 7).

וכל בכור בהמה AND ALL THE FIRSTBORN OF BEASTS — because they worshipped these as gods. When the Holy One, blessed be He, exacts punishment from a nation, He punishes their gods at the same time (Genesis Rabbah 96:5).

לא יחרץ כלב לשנו NO DOG SHALL חרץ HIS TONGUE — I say that it has the meaning of sharpening: “no dog shall whet his tongue”. So, too: (Joshua 10:21) “לא חרץ his tongue against any of the children of Israel”, i. e. “none whetted”; (II Samuel 5:24) “then תחרץ” — then thou shalt utter a sharp sound; (Isaiah 41:15) “a threshing-sledge חרוץ” i. e. sharp; (Proverbs 21:5) “the plans of a חרוץ” — of “an acute and sharp man”; (Proverbs 10:4) “the hand of the חרוצים maketh rich”, i. e. the hand of the acute — of sharp merchants.

אשר יפלה meant THAT HE MAKETH A DIFFERENCE.

וירדו כל עבדיך AND ALL THY SERVENTS SHALL COME DOWN [UNTO ME] — He showed respect to the king, for as a matter of fact ultimately Pharaoh himself came down to him at night, (Exodus 12:31) “And he said, Arise, go out from the midst of my people”; but Moses did not at the outset say to him, “And thou shalt come down to me and shalt prostrate thyself”, out of respect for the king, (Exodus Rabbah 7:3)

אשר ברגליך (lit., who are at thy feet) — who go after (follow) thy counsel and ways.

ואחרי כן אצא AND AFTER THAT I WILL GO OUT, with all my people, from thy land.

ויצא מעם פרעה AND HE WENT OUT FROM PHARAOH — After he had concluded his words he went forth from his presence.

בחרי אף IN FIERCENESS OF WRATH because he (Pharaoh) had said to him, (Exodus 10:28) “Do not again see my face.

למען רבות מופתי SO THAT MY WONDERS MAY BE MULTIPLIED (more lit., so that my wonders may be many) — referring not to one wonder alone (the slaying of the firstborn) but to the slaying of the firstborn, the division of the Red Sea and the overthrowing of the Egyptians in it.

ומשה ואהרן עשו וגו׳ AND MOSES AND AARON DID etc. — It (Scripture) has already written this in the description of all the preceding wonders, and it repeats it here only in order to connect it with the chapter which comes after this (as giving a reason why the commands in the next chapter were given to Aaron as well as to Moses; cf. Rashi’s comment on the following verse).