Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
The following commentary covers Chapters 16 and 17.
But now the difficulties of the way arrive. They travel three days without water-a sad effect, in appearance, of such a deliverance; and then the water is bitter when they find it. If death has delivered them from the power of the enemy, it must become known in its application to themselves; bitter to the soul, it is true, but, through grace, refreshment and life, for "in all these things is the life of the spirit." It is death and the application of the cross to the flesh practically, after the deliverance; but the wood-Christ's part on the cross, I doubt not-makes it sweet, and refreshment too. Thereupon we have the twelve wells and seventy palm-trees [See Note #1] -types, it seems to me, of those living springs and of that shelter which have been provided, through instruments chosen of God, for the consolation of His people.
Here we have the principle of the people's responsibility and their obedience, put as a condition of their well-being under God's government. Still, however, the part of the history from the Red Sea to Sinai is always grace. The Sabbath-rest of the people-is established in connection with Christ, the true bread of life, who gives it. Then comes the Spirit-living waters which come out of the rock; but with the presence of the Holy Ghost comes conflict, and not rest. Yet Christ, typified here by Joshua, of whom mention is now made for the first time, places Himself spiritually at the head of His people. True rest is by Christ, the bread come down from heaven, and this comes first, before conflict, though man could not really enjoy it by that bread alone, that is Christ incarnate, without death and redemption coming in. Unless we eat the flesh and drink the blood, there is no life to taste and enjoy the bread. But, as yet, the people are characterised by redemption, and their exercises and blessings are under grace. The question of direct access to God is not yet brought before us. The rock indeed is smitten-as it must be to have the living water at all; but this is the figure of what is historical, the event of Christ's death, not the figure of access to God within the veil. It is all the earthly part of God's ways, even in grace.
However sure of victory they may be in fighting the Lord's battles, the entire dependence of the people, at every moment, on the divine blessing, is presented to us in this, that if Moses (who with the rod of God represents to us His authority on high) keeps not his hands lifted up, the people are beaten by their enemies. Nevertheless, Aaron the high priest, and Hur (purity?) maintain the blessing, and Israel prevails. The cause was a hidden one. Sincerity, valiant efforts, the fact that the battle was God's battle, were, though right, of no avail-all depended upon God's blessing from on high. One would have thought, indeed, that if God made war, and unfurled the banner, it would soon be over; but no! from generation to generation He would make war upon Amalek. For, if it was the war of God, it was in the midst of His people.
The Lord adopted this number in His two closing missions of the disciples to Israel.