Notes on the Bible, by Albert Barnes, , at sacred-texts.com
According to their journeys - The Israelites rested at two stations before they reached Rephidim, namely, Dophkah and Alush Num 33:12-14. Dophkah was in the Wady Sih, a day's journey from the Wady Nasb. The wilderness of Sin Exo 16:1 properly speaking ends here, the sandstone ceases, and is replaced by the porphyry and granite which belong to the central formation of the Sinaitic group. Alush may have been near the entrance to the Wady Sheikh.
Rephidim - (Variously placed at Feiran at the base of Mount Serbal, or at the pass of El Watiyeh.)
Tempt the Lord - It is a general characteristic of the Israelites that the miracles, which met each need as it arose, failed to produce a habit of faith: but the severity of the trial, the faintness and anguish of thirst in the burning desert, must not be overlooked in appreciating their conduct.
The rock in Horeb - (a rock situated, according to Arab tradition, in Wady Feiran. Horeb was a name given to the whole desert of Sinai and subsequently attached to the mountain. Palmer).
It is questioned whether the water thus supplied ceased with the immediate occasion; see Co1 10:4, the general meaning of which appears to be that their wants were ever supplied from Him, of whom the rock was but a symbol, and who accompanied them in all their wanderings.
Massah ...Meribah - See the margin. On the importance of this lesson see our Lord's words, Mat 4:7.
Then came Amalek - The attack occurred about two months after the Exodus, toward the end of May or early in June, when the Bedouins leave the lower plains in order to find pasture for their flocks on the cooler heights. The approach of the Israelites to Sinai would of course attract notice, and no cause of warfare is more common than a dispute for the right of pasturage. The Amalekites were at that time the most powerful race in the Peninsula; here they took their position as the chief of the pagans. They were also the first among the pagans who attacked God's people, and as such were marked out for punishment (see the marginal references).
Joshua - This is the first mention of the great follower and successor of Moses. He died at the age of 110, some 65 years after this transaction. His original name was Hosea, but Moses calls him by the full name, which was first given about forty years afterward, as that by which he was to be known to succeeding generations. From this it may perhaps be inferred that this portion of Exodus was written, or revised, toward the end of the sojourn in the wilderness.
The rod of God - See Exo 4:20. The hill is supposed to be the height now called Feria an the north side of the plain Er Rahah; (or, Jebel Tahuneh over Feiran. Palmer).
Hur - Again mentioned with Aaron, in Exo 24:14. He was grandfather of Bezaleel, the great sculptor and artificer of the tabernacle, Exo 31:2-5, and belonged to the tribe of Judah. (See Ch1 2:18-20.)
The act represents the efficacy of intercessory prayer - offered doubtless by Moses - a point of great moment to the Israelites at that time and to the Church in all ages.
Until the going down of the sun - The length of this first great battle indicates the strength and obstinacy of the assailants. It was no mere raid of Bedouins, but a deliberate attack of the Amalekites, who had been probably thoroughly trained in warfare by their struggles with Egypt.
With the edge of the sword - This expression always denotes a great slaughter of the enemy.
In a book - in the book, i. e. the book which contained the history of God's dealings with His people. Moses was further instructed to impress the command especially on the mind of Joshua, as the leader to whom the first step toward its accomplishment would be entrusted on the conquest of Canaan. The work was not actually completed until the reign of Hezekiah, Ch1 4:43.
Jehovah-nissi - See the margin, "Jehovah my banner." As a proper name the Hebrew word is rightly preserved. The meaning is evidently that the name of Yahweh is the true banner under which victory is certain; so to speak, the motto or inscription on the banners of the host. Inscriptions on the royal standard were well known. Each of the Pharaohs on his accession adopted one in addition to his official name.
Because the Lord hath sworn - This rendering is incorrect. Our translators regard the expression as a solemn asseveration by the throne of God. However, to this the objections are insuperable; it has no parallel in Scriptural usage: God swears by Himself, not by His Throne. As the Hebrew text now stands the meaning is more satisfactorily given in the margin.
An alteration, slight in form, but considerable in meaning, has been proposed with much confidence, namely, נס nês, "standard" for כסא kı̂ssê', "throne"; thus connecting the name of the altar with the sentence. Conjectural emendations are not to be adopted without necessity, and the obvious a priori probability of such a reading makes it improbable that one so far more difficult should have been substituted for it. One of the surest canons of criticism militates against its reception. As it stands, the text was undoubtedly that which was alone known to the Targumists, the Samaritan, the Syriac, the Latin and the Arabic translators. The Septuagint appears to have had a different reading: ἐν χειρὶ κρυφαίᾳ πολεμεῖ en cheiri kruphē polemeō.