“And the L-RD spoke unto Moses in Mount Sinai, saying: Speak unto the children of Israel, and say unto them: When ye come into the land which I give you, then shall the land keep a Sabbath unto the L-RD.” – Leviticus 25:1-2, JPS 1917 Tanach
The Torah, specifically, mentions that the commandment of Shemitah, wherein the land is to lie fallow every seven years, “a Sabbath unto the L-RD,” was given on Mount Sinai. Why is this particular commandment, singled out, as being given at Mount Sinai? The Sages say, that this serves as a reminder that all the commandments, not only the Decalogue – the Ten Commandments – were given at Sinai. Yet, this still does not answer the question, why is the commandment of Shemitah given prominence?
Shemitah is a commandment that requires strong emunah (faith): for it is the trust in HaShem to provide enough crops in the previous year, to eat, while the land lies fallow, until the third year, when the harvest arrives. Emunah (faith), the essential element that was initially exhibited at Sinai, when B’nei Yisrael committed to observing the commandments, before actually hearing them (na’aseh v’nishmah) is exemplified in regard to the commandment of Shemitah.
This faith is integral to receiving the commandments on Sinai, inasmuch that G-d guarantees that during the seventh year, when the land lies fallow, He provides enough food from the previous year, to last throughout the seventh year, as well as the next year, when the crops are being planted. Only HaShem could make this guarantee; so, we see the connection.
The Tree of Life 