We often hear the expression “the end justifies the means”. What is implied is that sometimes it is legitimate to act in a wrong and even immoral manner as long as we do so for a justifiable purpose. This is strongly denied in our Sidra and in accordance to the interpretation Chazal give it.
Moshe conveys to the Israelites the command he received from Hakadosh Baruch Hu to build a Mishkan. Before he explains to the people what is expected of them, he first emphasizes that the Mitzvah of Shabbat must be kept. It is not permitted to desecrate Shabbat even to build a Mishkan. It seems that building a Mishkan is such a significant task that one may build even on Shabbat.
This is exactly what Moshe wants to avoid. He makes clear that although constructing a Mishkan carries with it a high priority and must be pursued without delay, building it does not allow one to tread upon other Mitzvot. In other words, the end does not justify the means.
We often overlook some of our understanding of right and wrong and feel that we are justified in doing so because we are aiming to fulfill a worthwhile task. This is exactly what the Torah through Moshe demonstrates that it is wrong. We must never step over the line of what is right.