In Exodus 15, Israel has left Egypt. They have passed through the Red Sea and the hostile Egyptians have been swallowed up by the water. They arrive at Marah and the people are thirsty, but the water of Marah is bitter and undrinkable. God shows Moses a stick and he throws it into the water, whereupon the water becomes sweet and drinkable. Both the passage through the Red Sea, and the bitter water that becomes sweet, are beautiful images of life that comes from death.
foreshadowing
These stories therefore point forward to a converted Israel in the future. Israel’s arrival at Marah is after the people have traveled through the desert for three days (Ex.15:22). On the third day, the bitter water becomes sweet. Israel is prophesied that after two days, on the third day, it will be raised up and made alive (Hos.6:1-2). We know from Peter that we must reckon with days of a thousand years (2 Pet. 3:8).
two thousand years
Those two days of a thousand years are almost over. Then Israel will (still) fulfill her royal and priestly task and the nations will be blessed through them. Israel will be set over the nations of the earth (Deut.28:1 and 13). We also find this depicted in the rest of history:
Exodus 15
27 And they came to Elim;
and there were twelve springs of water and seventy palm trees,
and they encamped there by the waters.
twelve and seventy
The number twelve of course speaks of Israel (12 sons of Jacob, 12 tribes, etc.). Israel is the source, the navel of the earth (Ezek.38:12 NKJV) and to them the words of God have been entrusted (Rom.3:2).
The seventy palm trees are a representation of the nations, see the list of nations in Genesis 10, where seventy nations are mentioned. Through Israel, in the future, all the peoples of the earth will share in the blessings of the word of God. What a wonderful prospect!