The classic question asked by Rashi regarding פרשת בהר, as to what does שמיטה have to do with הר סיני? Aren't all of the Mitzvot given on Mount Sinai? And the classic answer is that just as Shmitta was given on Mount Sinai, so, too, were all Mitzvot given on Mount Sinai. In other words, the Torah chose Shmitta as an apparent random example of a Mitzva given on Mount Sinai.
It seems that this is an incomplete answer. The question still remains as to why Shmitta, the Sabbatical year, was randomly chosen as the example of a law given at Sinai.
The real answer seems to be that the test of a Jew's true faith is in his wallet. Leaving the land fallow in the seventh year, and trusting completely in Hashem takes a great deal of faith. Our view of money, in general, also requires faith. Do we trust Hashem to reimburse us for the charity we give? Are we prepared to walk away from a business deal that promises great profits but is borderline ethical, because it is more important to do what is right in the "eyes of G-d?"
Shmitta is the example of a law given at Sinai to remind us that we must always rely on Hashem- especially in money matters.
Yesterday was 35 with ספירת העומר