Why the Repetition?
The book of Shemos-Exodus concludes with a description of the journey of the Jewish people in the desert.
“When the cloud rose up from over the Tabernacle, the children of Israel would set out on all their journeys. But if the cloud did not rise up, they did not set out until, the day that it rose.”
We know that every word in the Torah is precise and necessary to teach us something that we would not have known had the Torah not mentioned it. The Torah is extremely economical in its language. If something can be said in one word, the Torah will not use two words to express the same idea.
Any repetition that we may find in the Torah must be there to teach us something novel.
Based on the above premise, the question arises: why did the Torah have to add the negative statement that “if the cloud did not rise up, they did not set out until, the day that it rose”? Wasn’t it quite obvious from the statement in the preceding verse, that the people would set out on their journeys when the cloud rose up from the Mishkan, that if the cloud didn’t rise they would stay put?
A Double Stipulation
The answer to this question can be found in a parallel teaching of the Torah concerning the law of transactions. If one engaged in a transaction and makes it contingent on the other party meeting a certain condition, the transaction will not take effect if the condition is not met. However, the law is that it must be a “tnai kaful-double condition.” This means that the person must repeat the condition in its negative form. That means that he must add that if the condition is not met the transaction will be null and void.
The following is an example of this Talmudic principle cited by Maimonides in his Mishneh Torah:
“One who proposes to a woman and says, “If you will give me 200 zuz you shall be married to me with this dinar; if you will not give it to me you will not be married [to me].’”
In this situation the marriage will only be effective if she gives him the 200 zuz. If she fails to give it, she will not be married to this man, in accordance with his stipulation.
“If, however, he says to her, ‘If you will give me 200 zuz you shall be married to me with this dinar’ but fails to add the converse, ‘if you will not give me the 200zuz you will not be married to me,’ the condition is null and void and the marriage is effective, even if the condition was not met.”
This, the Talmud states is based on the Biblical story of the Sons of Reuven and Menasheh, who asked Moses for a share in the east side of the Jordan River. When Moses chastised them for not wanting to join their brethren in the conquest of Cana’an, they offered to join them first but then to return later to claim their shares on the east bank of the Jordan.
Moses accepted their offer and said to them:
“If you will do this thing, if you arm yourselves for battle before G‑d, and your army crosses the Jordan… and the land be conquered before G‑d – then afterwards you may return…”
Moses then added the same idea phrased in the negative:
“But, if you do not do so, then you will have sinned against G‑d…”
The fact that Moses had to stipulate that their right to the land on the east bank of the Jordan was contingent on their willingness to join their brethren, both in the affirmative and the negative, is the basis for the law that a condition in any transaction must be doubled; i.e., phrased in both the positive and in the negative.
What is the logic behind this requirement?
When a person attaches a condition to his or her transaction, we must be convinced that he or she is absolutely serious about that condition. It is possible that the condition may have been merely a flippant suggestion, a whim or wish. Perhaps the person did not mean that the transaction would be null and void if the condition were left unfulfilled. To demonstrate sincerity and seriousness about the condition, one must restate it in the negative. This confirms the notion that the condition is solid and non-negotiable.
Obsessed with the Journey
We may now apply the above to the repetition in our verse concerning the journey of the Jewish people in the desert.
If the Torah had only phrased the need to stay put as long as the cloud was hovering over the Mishkan, the Jewish people might have construed it as a stop sign rather than correctly understanding it to be a red light. In their eagerness to continue on their journey they might have misconstrued the full extent of the order to stay put because the Jewish mindset was never to stop journeying.
The Israelites were in a quandary when they stood in front of the Red Sea. What were they to do? They were sandwiched between the pursuing Egyptian forces and a foreboding sea; it was the proverbial place between a rock and hard place.
Our Sages tell us, based on hints in the text of the Torah, that the Jewish nation was divided into four camps in that moment. One wanted to surrender to the Egyptians and return to slavery. Another group said “let us fight them.” A third group was ready to drown themselves in the sea, and a fourth group started to pray to G‑d. As is well known, G‑d rejected all of these approaches and told Moses to command them to continue on their journey. It was precisely then that the sea split to facilitate the continuation of their journey.
The Rebbe explains that G‑d told them that their mission was to receive the Torah at Mount Sinai. It was not a time for any distraction from the mission, that they should forge ahead. There was no justification for any detour or hiatus. Their mission was to journey towards Mount Sinai and nothing, not even a sea, could stand in their way. Indeed, not even the need to pray to G‑d for salvation could stand in the way.
Once the Jews heard what their marching orders were, this obsession with journeying forward became programmed into their psyche. This thrust towards Sinai continued even after reaching Sinai and was directed towards their destination, the Promised Land, where they would implement the dictates of the Torah.
After they degenerated in the construction and worshipping of the Golden Calf, in order to continue on their journey without further mishap they required their journey to be imbued with a heavy dose of G‑dly energy. For this purpose, they had to build a Mishkan, a Sanctuary, around which they could encamp and reenergize themselves with heavy doses of spirituality that would rehabilitate and fortify them.
In order to maximize their absorption of the G‑dly energy, they had to rest near the Mishkan. If they were to hurry on before imbibing and internalizing the Divine radiance generated by the Sanctuary, their journey would not be successful. While they may have come closer to the Promised Land in the geographic sense of the word, their mindset would have been mired in a distant place, much closer to the depraved Egyptian mode. 
We can now understand why the Torah had to repeat the order to not resume their journey until the cloud rose from the Mishkan.
If not for the repetition that reinforced the order to cease traveling when the cloud hung over the Mishkan they would have reverted to their default positon of not staying in one place. Their desire to journey was by now so engrained in them that they would not have taken seriously the first part of the order.
The Torah therefore repeats the admonition of not travelling until the cloud lifted as a way of stating unequivocally: “if the cloud did not rise up, they did not set out until, the day that it rose.” This was G‑d’s way of saying don’t allow your spiritual zeal to compromise your need to absorb the G‑dly holiness while you are encamped around the Mishkan.
A Green Light
Our generation has been told to journey forward to the final Redemption, just as the Jews of that generation were told to journey towards the Promised Land, but with one caveat. Whereas the generation of the desert was not ready to enter the Promised Land because they needed frequent stops to erect the Mishkan and bask in its light for extended periods of time, our generation has been given the green light to journey without even a stop sign to slow down its progress towards the final Redemption.
The only parallel to that generation is that the need to journey forward has been programmed into our psyche. Therefore, absent a direct order from on High that we should pause, we follow our G‑dly instincts to forge ahead.
There was a time when the Sages of the past admonished us not to try to accelerate the Redemption because the time was not ripe. Our journey then was limited to living in the moment, surviving and even thriving; but the focus was not inordinately on the future. To be sure, there was never a time when Jews gave up on praying and yearning for Moshiach and Redemption, but their primary focus was on the here and now.
As we have come closer to the Messianic Age, our Sages of the last few centuries have told us that the focus has changed, because we are nearing the very end of our journey. Now, we must look to do everything in our power to hasten and prepare for the Redemption, which we will do by increasing our observance of the Mitzvos and the study of Torah, particularly those parts of Torah dealing with Redemption and promoting greater Jewish unity.