Parshas Truma - Rav Zalman Sorotzkin - Returning The Money To Mitzrayim?
Rav Zalman Sorotzkin, in Oznayim LaTorah, offers the following pshat on why the Parsha of Truma follows the parshiyos of Yisro and Mishpatim. When the Bnei Yisrael left Mitzrayim they were told to "borrow" the riches of their Mitzri neighbors. Later on it became clear that they were never intending to repay this "loan".
At Har Sinai, Hashem told them, "Lo Signov," and then in Mishpatim they learned some of the finer details about dealing with other people's money. The ehrlicher Jews among them started to get worried about the money of questionable kashrus that they had in their possession from the Mitzrim. They thought that maybe this was a subtle hint from Hashem that they ought to go back and return the money.
Hashem therefore tells them in the beginning of the parsha, "ViYikchu Li Truma. If you think the money you have is not kosher, then come give it to me. Use it for my home, the Mishkan, that is rooted in honesty, since it is legitimately yours. If it is kosher enough for me to use, it is certainly kosher enough for you to use, and there is no need to return it to Mitzrayim."