This Land Was Made for You and Me: Shmitta Then and Now Behar 5784

(ד) וּבַשָּׁנָ֣ה הַשְּׁבִיעִ֗ת שַׁבַּ֤ת שַׁבָּתוֹן֙ יִהְיֶ֣ה לָאָ֔רֶץ שַׁבָּ֖ת לַיהֹוָ֑ה שָֽׂדְךָ֙ לֹ֣א תִזְרָ֔ע וְכַרְמְךָ֖ לֹ֥א תִזְמֹֽר׃ (ה) אֵ֣ת סְפִ֤יחַ קְצִֽירְךָ֙ לֹ֣א תִקְצ֔וֹר וְאֶת־עִנְּבֵ֥י נְזִירֶ֖ךָ לֹ֣א תִבְצֹ֑ר שְׁנַ֥ת שַׁבָּת֖וֹן יִהְיֶ֥ה לָאָֽרֶץ׃

Leviticus 25:4-5

(4) But in the seventh year the land shall have a sabbath of complete rest, a sabbath of יהוה: you shall not sow your field or prune your vineyard. (5) You shall not reap the aftergrowth of your harvest or gather the grapes of your untrimmed vines; it shall be a year of complete rest for the land.

In the Shmita year, debts are to be forgiven, agricultural lands to lie fallow, private land holdings to become open to the commons, and staples such as food storage and perennial harvests to be freely redistributed and accessible to all.
--MyJewishLearning.com

סנהדרין ל״ט א:י״ב-י״ג

אתא ההוא תלמידא א"ל מ"ט דשביעתא א"ל השתא אמינא לכו מילתא דשויא לתרוייהו אמר הקב"ה לישראל זרעו שש והשמיטו שבע כדי שתדעו שהארץ שלי היא ו

Sanhedrin 39a:12-13

In the meantime, a certain student came before Rabbi Abbahu and said to him: What is the reason for the mitzva of the Sabbatical Year? Rabbi Abbahu said to them: Now I will tell you something that is fit for the two of you. Rabbi Abbahu continued: The Holy Blessed One said to the Jewish people: Sow for six years, and withhold sowing during the seventh year, so that that you will know that the land is Mine.

The commandment of Shmita encompasses the extremes of both these fundamentals. In the commandment, there are the societal and the faith-inspired elements. It has the faith-based aspect in which a person declares that the land is not theirs (by releasing it for a year)... And, in the societal element, the Torah tells us another purpose for Shmita is “in the seventh you shall release it and let it lie fallow. Let the needy among your people eat of it.” The concern for society is taken to the extreme in this commandment. The owner of the field must relinquish ownership over the field and allow any person to use it. The property owner and poor person are on equal footing vis-a-vis the field and the produce. This is in contrast to other forms of charity in which the owners of the goods are giving of their own goods.
--Rabbi Haim Sabato

סנהדרין כ״ו א:ו׳-ז׳

קשו בה בני רחבה האי משרבו האנסים משרבו התגרין מיבעי ליה אלא בתחילה היו אומרים אחד זה ואחד זה פסולין משרבו האנסין ומאי נינהו ארנונא כדמכריז רבי ינאי פוקו וזרעו בשביעית משום ארנונא חזרו לומר אוספין כשרין סוחרין פסולין

Sanhedrin 26a:6-7

Once the tax collectors grew abundant it was permitted to gather the produce of the Sabbatical Year. And what tax did they collect? Arnona, which was a heavy tax on property collected both during the Sabbatical Year and in other years, placing pressure on those observing the Sabbatical Year. As Rabbi Yannai proclaimed: Go out and sow the fields during the Sabbatical Year due to the arnona that you must pay. Once this happened, the Sages then said: Gatherers of the produce of the Sabbatical Year are fit to bear witness, as they were no longer viewed as transgressors, but merchants who trade in this produce are still disqualified.

ויקרא רבה א׳:א׳

((תהלים קג, כ): גִּבֹּרֵי כֹחַ עֹשֵׂי דְבָרוֹ, בַּמֶּה הַכָּתוּב מְדַבֵּר, אָמַר רַבִּי יִצְחָק בְּשׁוֹמְרֵי שְׁבִיעִית הַכָּתוּב מְדַבֵּר, בְּנֹהַג שֶׁבָּעוֹלָם אָדָם עוֹשֶׂה מִצְוָה לְיוֹם אֶחָד, לְשַׁבָּת אֶחָת, לְחֹדֶשׁ אֶחָד, שֶׁמָּא לִשְׁאָר יְמוֹת הַשָּׁנָה, וְדֵין חָמֵי חַקְלֵיהּ בָּיְרָה כַּרְמֵיהּ בָּיְרָה וְיָהֵב אַרְנוֹנָא וְשָׁתִיק, יֵשׁ לְךָ גִּבּוֹר גָּדוֹל מִזֶּה.

Vayikra Rabbah 1:1

“Mighty in strength, who perform His bidding” (Psalms 103:20) – regarding whom is the verse speaking? Rabbi Yitzḥak said: The verse is speaking of those who observe the Sabbatical Year. The way of the world is that a person performs a mitzva for one day, for one week, for one month. But does one do so for the rest of the days of the year? Yet this one sees his field fallow, his vineyard fallow, and pays his land tax and remains silent. Is there anyone mightier than that?

Rambam lists each aspect of Shmita and Yovel as separate positive commandment:
134: to render all that grows from the ground ownerless during Shmita
135: to rest from all agricultural work in the seventh year
136: to sanctify the 50th year
137: to free all slaves during Yovel
138: to return all lands to their owners during Yovel
139: that urban land can only be redeemed until the end of the year
In addition to these, Rambam adds commandment 140, which is to count the years within the Shmita and Yovel cycles. This responsibility lies with the Sanhedrin, the rabbinical high court.
Hazon Shemitta Sourcebook