How did Bnei Yisrael have acacia wood in the desert? Some commentaries suggest that it grew in nearby forests, or perhaps it was available for purchase from merchants they encountered in the desert.
Rashi, on the other hand, maintains that Bnei Yisrael left Egypt with a supply of acacia wood intended for use in the Mishkan. The source for this is a Midrashic account that Rashi cites in the name of Rabbi Tanchuma: “Our forefather Yaakov foresaw with Ruach Hakodesh, Divine intuition, that Bnei Yisrael were destined to build a Mishkan in the desert. He therefore brought cedars to Egypt and planted them, and instructed his sons to take them along when they left Egypt.”
Why did Yaakov go to the trouble of bringing trees with him from the Land of Israel and planting them in Egypt? Surely he knew that Bnei Yisrael would have other opportunities to obtain acacia wood. Why didn’t he rely on Bnei Yisrael’s simply buying the wood, or procuring it from a nearby forest? Evidently, Yaakov had additional reasons for bringing the wood with him.
Rashi alludes to these motives by citing the teaching in the name of Rabbi Tanchuma, whose name comes from the Hebrew word tanchumin—consolations.
The acacia trees that Yaakov planted in Egypt were a visible symbol of his prophecy that one day G‑d would free Bnei Yisrael from Egypt and command them to build a Mishkan for Him in the desert. In the most dark and difficult moments of their slavery, these trees served as a source of hope and comfort. Seeing the trees from the Land of Israel reminded and reassured Bnei Yisrael that they would not remain exiled forever; G‑d would soon bring them home, back to the Land of Israel from which they—and the trees—originated.
Although he knew that Bnei Yisrael could obtain the acacia wood through other means, Yaakov bought them along from the Land of Israel to provide solace to his descendants throughout their bitter exile.
—Likkutei Sichos, vol. 31, pp. 142–147
