He sent darkness, and made it dark - Exodus 10:21-23.
And they rebelled not against his word - More literally, "his words." The reference is to Moses and Aaron; and the idea, as expressed here, is that they were obedient to the command of God; that they went and did what he ordered them; that, although he required them to go before a mighty and proud monarch, to denounce against him the vengeance of heaven, and to be the instruments of bringing upon the land unspeakably severe judgments, yet they did not shrink from what God commanded them to do. They were true to his appointment, and showed themselves to be faithful messengers of God. Others, however, suppose that this refers to the Egyptians, and that it is to be taken as a question: "And did they not rebel against his word?" The language might bear this, and the translators of the Septuagint seem to have so understood it, for they render it, "And they rebelled against his words." But the most natural construction is that in our common version, and the design is evidently to commend the boldness and the fidelity of Moses and Aaron.

They rebelled not against his word - Instead of ולא מרו velo maru, "they rebelled," some think that a ש shin has been lost from before the word, and that it should be read ולא שמרו velo shamru, "they did not observe or keep his word." Or the words may be spoken of Moses and Aaron; they received the commandment of God, and they did not rebel against it. They believed what he had spoken, and acted according to his orders. It could not be spoken of the Egyptians; for they rebelled against his words through the whole course of the transactions.

He sent darkness, and made it dark; and they (o) rebelled not against his word.
(o) Meaning, Moses and Aaron.

He sent darkness, and made it dark,.... The land of Egypt; either he, God, or it, darkness, made it dark, or it was made dark; the Targum is,
"made them dark;''
that is, the Egyptians; darkness was a messenger of the Lord's, who forms the light and creates darkness; it came at his word and covered all the land, excepting the dwellings of Israel; even a thick darkness that might be felt, so that the Egyptians could not see one another, nor rise from their place for three days together; such as sometimes rises at sea, and is said to be so dark, that for five days together day and night are the same; this was the ninth of the ten plagues, Exodus 10:21 and was an emblem of the darkness which is on the minds of men in an unregenerate state; who are covered with gross darkness, and are even darkness itself; which is universal as to persons, and the powers and faculties of their souls concerning divine things: and it also bears some resemblance to the darkness which will be in the kingdom of the beast upon the pouring out of the fifth vial, or plague, on spiritual Egypt, Revelation 16:10.
And they rebelled not against his word: the plague of darkness, and the rest of the plagues which God commanded; these, as they were his servants, were not disobedient to him, they came at his word; see Psalm 105:31, so Jarchi interprets it; or else Moses and Aaron, who were sent of God to inflict those plagues, did not refuse to obey the divine orders; though Pharaoh threatened them hard, yet they feared not the wrath and menaces of the king, but did as the Lord commanded them. Aben Ezra, Kimchi, and Ben Melech, mention both these senses, but the latter seems most agreeable. The Septuagint, Syriac, and Arabic versions, leave out the word "not"; and so some copies of the Vulgate Latin version, and Apollinarius in his metaphrase, "and they rebelled against his word"; that is, the Egyptians did not hearken to the word of the Lord, nor to the signs and wonders he wrought, but their hearts were hardened, and they would not let Israel go. But this is contrary to the original text; though Arama interprets it of them, that they did not rebel, but confessed this miracle, which being the greatest of all, as he observes, is first mentioned. Dr. Lightfoot (y) thinks it is to be understood of Israel, and of some special part of obedience performed by them; which he takes to be circumcision, which they had omitted in Egypt, at least many of them, and was necessary to their eating of the passover, which was to be done in a few days, Exodus 12:48 and it was a fit time to perform this service while darkness for three days was upon the Egyptians; in which they were shut up by the Lord, that they might not take the opportunity against his people, now sore through circumcision.
(y) Works, vol. 1. p. 707.

The ninth plague is made prominent as peculiarly wonderful.
they rebelled not--Moses and Aaron promptly obeyed God (Hebrews 11:27); (compare Exodus. 7:1-11:10 and Psalm 78:44-51, with which this summary substantially agrees). Or, rather, the "darkness" here is figurative (Jeremiah 13:16), the literal plague of darkness (Exodus 10:22-23) being only alluded to as the symbol of God's wrath which overhung Egypt as a dark cloud during all the plagues. Hence, it is placed first, out of the historical order. Thus, "They rebelled not (that is, no longer) against His word," refers to the Egyptians. Whenever God sent a plague on them, they were ready to let Israel go, though refusing when the plague ceased.
his word--His command to let Israel go [HENGSTENBERG]. Of the ten plagues, only eight are mentioned, the fifth, the murrain of beasts, and the sixth, the boils, being omitted.

They - Moses and Aaron, who inflicted that plague after Pharaoh had threatened them.