Notes on the Bible, by Albert Barnes, , at sacred-texts.com
With frogs - Some months appear to have elapsed between this and the former plague, if the frogs made their appearance at the usual time, that is in September. The special species mentioned here is of Egyptian origin. This plague was, like the preceding, in general accordance with natural phenomena, but marvelous both for its extent and intensity, and for its direct connection with the words and acts of God's messengers. It had also apparently, like the other plagues, a direct bearing upon Egyptian superstitions. There was a female deity with a frog's head, and the frog was connected with the most ancient forms of nature-worship in Egypt.
Into thine house - This appears to have been special to the plague, as such. It was especially the visitation which would be felt by the scrupulously-clean Egyptians.
Kneadingtroughs - Not dough, as in the margin. See Exo 12:34.
The magicians would seem to have been able to increase the plague, but not to remove it; hence, Pharaoh's application to Moses, the first symptoms of yielding.
Glory over me - See the margin, "have honor over me," i. e. have the honor, or advantage over me, directing me when I shall entreat God for thee and thy servants.
When - Or by when; i. e. for what exact time. Pharaoh's answer in Exo 5:10 refers to this, by tomorrow. The shortness of the time would, of course, be a test of the supernatural character of the transaction.
Villages - Literally, enclosures, or courtyards.
It is observed by Hebrew commentators that the nine plagues are divided into three groups: distinct warnings are given of the first two plagues in each group; the third in each is inflicted without any previous notice; namely, the third, lice, the sixth, boils, the ninth, darkness.
The dust of the land - The two preceding plagues fell upon the Nile. This fell on the earth, which was worshipped in Egypt as the father of the gods. An special sacredness was attached to the black fertile soil of the basin of the Nile, called Chemi, from which the ancient name of Egypt is supposed to be derived.
Lice - The Hebrew word occurs only in connection with this plague. These insects are generally identified with mosquitos, a plague nowhere greater than in Egypt. They are most troublesome toward October, i. e. soon after the plague of frogs, and are dreaded not only for the pain and annoyance which they cause, but also because they are said to penetrate into the body through the nostrils and ears.
The finger of God - This expression is thoroughly Egyptian; it need not imply that the magicians recognized Yahweh, the God who performed the marvel. They may possibly have referred it to as a god that was hostile to their own protectors.
Cometh forth to the water - See the Exo 7:15 note. It is not improbable that on this occasion Pharaoh went to the Nile with a procession in order to open the solemn festival, which was held 120 days after the first rise, at the end of October or early in November. At that time the inundation is abating and the first traces of vegetation are seen on the deposit of fresh soil.
The plague now announced may be regarded as connected with the atmosphere, also an object of worship.
Swarms of flies - Generally, supposed to be the dog-fly, which at certain seasons is described as a plague far worse than mosquitos. Others, however, adopt the opinion that the insects were a species of beetle, which was reverenced by the Egyptians as a symbol of life, of reproductive or creative power. The sun-god, as creator, bore the name Chepera, and is represented in the form, or with the head, of a beetle.
I will sever ... - This severance constituted a specific difference between this and the preceding plagues. Pharaoh could not of course attribute the exemption of Goshen from a scourge, which fell on the valley of the Nile, to an Egyptian deity, certainly not to Chepera (see the last note), a special object of worship in Lower Egypt.
To your God - Pharaoh now admits the existence and power of the God whom he had professed not to know; but, as Moses is careful to record, he recognizes Him only as the national Deity of the Israelites.
In the land - i. e. in Egypt, not beyond the frontier.
The abomination - i. e. an animal which the Egyptians held it sacrilegious to slay. The ox, bull, or cow, is meant. The cow was never sacrificed in Egypt, being sacred to Isis, and from a very early age the ox was worshipped throughout Egypt, and more especially at Heliopolis and Memphis under various designations, Apis, Mnevis, Amen-Ehe, as the symbol or manifestation of their greatest deities, Osiris, Atum, Ptah, and Isis.
Three days' journey - See the Exo 3:18 note.