The Gemara (כתובות סב,ב) brings a story of two great rabbis (רבי ורבי יוסי בן זימרא) that were marrying
their children off to each other. In those times, after getting engaged the boy usually would go to study Torah in a Yeshiva away from home for a few years before getting married. This Chattan, the son of the big rabbi, planned to go to study for 12 years. The girl’s side felt it was much too long and devised aplan, they a sked the girl to walk past the boy for him to see her, and so she did. Once the boy saw her, he changed his plans, to go for only six years. The family still felt that was much too long and therefore asked the girl to repeat and walk again, and when the boy saw her again, he canceled his plans and decided to get married right away. When the boy met his father, he was very embarrassed for forgoing Yeshiva time because of the interest in his new wife.
When his father realized his feelings, he reassured his son by telling him that Hashem Himself did the same; as Chazal explain that after we were taken out of Egypt, we were “engaged” to Hashem and Hashem’s actual marriage would be at the building of the Bet Hamikdash which was initially intended to take place when the Nation of Israel would enter the land of Israel. But something caused Hashem to “reconsider” as He couldn’t wait that long and asked to build the Mishkan immediately so he can marry Am-Yisrael right away without delay. Now what was that thing that He found in the Nation of Israel that made Him feel this way?
When one moves to a new house, he usually orders a moving company in order to take all his
belongings. Some of those belongings are more important and some are less, but there are always some things that are very important which the person moving would never leave behind.
When our nation left Egypt they didn’t have moving trucks to carry their belongings; they had to carry them on animals and on their shoulders, so they were very limited in terms of what they could actually take with them. They probably had to choose the most important things and leave behind the less important.
What were those very important things which the people took with them as they left their houses in
Egypt? In our Parasha, Hashem tells Moshe to build the Mishkan with עצי שיטים, Acacia trees. Rashi asks where exactly they were supposed to find such woods in the desert, which is a land of nothing but sand, and answers with a beautiful insight: that Yaakov Avinu foresaw that we would build the Mishkan and therefore brought with him young Acacia trees to Egypt to plant them, and asked his children that they uproot and take them along when they leave Egypt. Now, one can just imagine the size of those trees, as they were planted 210 years prior.
The Ibn Ezra says they were huge and many of them were needed, which gives us an idea of what Bnei Yisrael took with them in their limited bundles. Instead of taking their belongings, they found room for tree trunks that were extremely big and heavy, just to express their unlimited love to Hashem and build the Mishkan with it.
Other items which they have found more important than their belongings to take with them were the drums, as we see that when they sang to Hashem after crossing the river and seeing the Egyptians drown, all the women took out their drums and started playing it while singing שירת הים. Rashi says the reason they had those drums with them is because they knew a miracle would happened and after that miracle they would want to sing praises to Hashem with those drums. Now a drum is not a very small instrument, and still they all felt they should take it in order to honor Hashem with their singing. The nation also carried along with them gold and silver vessels which they took from the Egyptians. But those vessels were not things they wanted, since they were scared the Egyptians would eventually chase after them to get those vessels back, as indeed happened afterwards (רש״י בשמות יד,ו). This also explains why Hashem had to plead with them to take the vessels, which clearly indicates they weren’t interested in taking them.(שמות יא,ב ורש״י שם)
We learned from the above that they took with them chunks of wood to build the Mishkan for Hashem, and they carried the drums to be able to play it while singing to Hashem, and they took the vessels which put them in danger to fulfill the request of Hashem; but what about packing for the journey, the most important thing before leaving to a desert which has nothing but sand and a burning sun?
We all know that before we go on a trip the first thing we make sure to take with us is enough food, or make sure that the place we will be visiting has food; but when we left Egypt we didn’t do any of that since Hashem told us not to take any food, aside for the Matsot, as the Passuk says: (שמות יב,לט) ״וגם צדה לא עשו להם״ , Rashi points out that they didn’t have food with them:מגיד שבחן של ישראל שלא אמרו היאך נצא למדבר בלא צדה אלא האמינו והלכו Rashi concludes with beautiful words which summarize everything we wrote: that Am-Yisrael as a bride to Hashem, went out to the desert without food and on the same time carrying things that would only be a burden to them: הוא שמפורש בקבלה (ירמיהו ב) זכרתי לך חסד נעוריך אהבת כלולותיך לכתך אחרי במדבר בארץ לא זרועה
Hashem says to Israel: I remember the devotion of your youth, your love as a bride— how you followed me in the desert, in a land not sown. Now when we have such a Kalla as Am-Yisrael, how would the Chatan be able to wait until they reach the land of Israel? This is precisely why Hashem couldn’t wait and asked to speed up the wedding day by building the Mishkan immediately.