Exodus 23:11

but the seventh year thou shalt exempt it from labour, and give up the fruit of it to be eaten by the poor of My people; and what they leave shall be eaten by the beasts of the field. And in like manner shalt thou do with thy vine and olive grounds.

BUT THE SEVENTH YEAR ‘TISHM’TENAH U’N'TASHTAH’ (THOU SHALT LET IT REST AND LIE FALLOW). “Tishm’tenah — by not tilling it. U’n'tashtah by not eating of its produce after ‘the time of removal.’ Another interpretation: Tishm’tenah — from real work, such as plowing and sowing; u’n'tashtah — from hoeing or manuring it.” This is Rashi’s language. But it is not correct, for according to the law of the Torah we have only been warned against plowing and sowing in the seventh year, but hoeing and manuring, and even weeding, hoeing under the vines, and cutting away thorns, and all other forms of agricultural work, are not forbidden by law of the Torah. This is the conclusion that the Rabbis came to [after a discussion of this matter] at the beginning of Tractate Moed Katan in the Chapter Mashkin: that the Merciful One forbade only plowing and sowing in the seventh year, but did not prohibit secondary kinds of work [such as hoeing, manuring, etc.], which are all forbidden only by Rabbinic ordinance, and the verse mentioned [there in the Talmud] in connection with these secondary kinds of work is a mere support in the Scriptural text. Note 449. Similarly, the law of “removal” is not derived from this verse [as Rashi explained here].
Rabbi Abraham ibn Ezra wrote: “Tishm’tenah means: every creditor ‘shamot’ (shall release) that which he hath lent unto his neighbor. — U’n'tashtah means that you should not sow your field.” But it is not a correct comment. Instead, [the true explanation is that] Scripture first said, six years thou shalt sow and gather in the increase thereof, but the seventh year ‘tishm’tenah’ — you should not sow your land; u’n'tashtah — you should not gather in its increase, but instead you are to leave it so that the poor of your people and the beasts of the field may eat the fruits of the tree and the produce of the vineyard. In a similar sense is the verse, ‘v’nitash’ the seventh year, [which thus means: “and we will not gather in the increase of the field in the seventh year”].

לכרמך ולזיתך, parallel to what the Torah legislated concerning the grain harvest. It is a rule in the Torah to mention these agricultural products under the headings ofדגן, תירוש, יצהר, meaning different types of grain, orchard products, and oil produced by the olive trees. The legislation includes all food products grown from the soil.

תשמטנה, a reference to sh’mittat kessaphim, relinquishing outstanding overdue debts at the end of the agricultural Sh’mittah year. The legislation is spelled out in greater detail in Deuteronomy 15,2 .

ונטשתה ואכלו אביוני עמך, during the agricultural sh’mittah year the poor will also share in all the crops.

ויתרם, after the poor have taken what they want,

תאכל חית השדה, the poor people had first claim. We have been taught in Taanit 20 that one must not feed the dogs food which is fit for human consumption.