Exodus 23:10-13: And six years thou shalt sow thy land, and shalt gather in the fruits thereof: But the seventh year thou shalt let it rest and lie still; that the poor of thy people may eat: and what they leave the beasts of the field shall eat. In like manner thou shalt deal with thy vineyard, and with thy oliveyard. Six days thou shalt do thy work, and on the seventh day thou shalt rest: that thine ox and thine ass may rest, and the son of thy handmaid, and the stranger, may be refreshed. And in all things that I have said unto you be circumspect: and make no mention of the name of other gods, neither let it be heard out of thy mouth.

From EASTON'S BIBLE DICTIONARY: Sabbatical Year:
Every seventh year, during which the land, according to the law of Moses, had to remain uncultivated (Leviticus 25:2-7; comp. Exodus 23:10, 11, 12; Leviticus 26:34, 35). Whatever grew of itself during that year was not for the owner of the land, but for the poor and the stranger and the beasts of the field. All debts, except those of foreigners, were to be remitted (Deuteronomy 15:1-11). There is little notice of the observance of this year in Biblical history. It appears to have been much neglected (2 Chronicles 36:20, 21).

From EASTONS' BIBLE DICTIONARY - Jubilee:
A joyful shout or clangour of trumpets, the name of the great semi-centennial festival of the Hebrews. It lasted for a year. During this year the land was to be fallow, and the Israelites were only permitted to gather the spontaneous produce of the fields (Leviticus 25:11, 12). All landed property during that year reverted to its original owner (13-34; 27:16-24), and all who were slaves were set free (25:39-54), and all debts were remitted.
The return of the jubilee year was proclaimed by a blast of trumpets which sounded throughout the land. There is no record in Scripture of the actual observance of this festival, but there are numerous allusions (Isaiah 5:7, 8, 9, 10; 61:1, 2; Ezekiel 7:12, 13; Nehemiah 5:1-19; 2 Chronicles 36:21) which place it beyond a doubt that it was observed.
The advantages of this institution were manifold. "1. It would prevent the accumulation of land on the part of a few to the detriment of the community at large. 2. It would render it impossible for any one to be born to absolute poverty, since every one had his hereditary land. 3. It would preclude those inequalities which are produced by extremes of riches and poverty, and which make one man domineer over another. 4. It would utterly do away with slavery. 5. It would afford a fresh opportunity to those who were reduced by adverse circumstances to begin again their career of industry in the patrimony which they had temporarily forfeited. 6. It would periodically rectify the disorders which crept into the state in the course of time, preclude the division of the people into nobles and plebeians, and preserve the theocracy inviolate."

From the LDS BIBLE DICTIONARY - Sabbatical Year: As was the seventh day in every week and the seventh month in every year, so also was every seventh year consecrated to the Lord. The land, inasmuch as it was the Lord's, was to keep a Sabbath unto him (Leviticus 25:2-7). In this year the self-sown produce of the arable lands was to be left for the poor and the beasts of the field; and the fruit of the unpruned vineyards (and oliveyards) was not to be harvested, but to be left to the owner, his family and servants, the stranger sojourning with him, his cattle, and the wild beasts. A release of debts owed by Israelite to Israelite was made. The year was intended to be not simply a year of leisure, but also one of religious instruction and exercises. To mark this, at the Feast of Tabernacles (i.e., at the commencement of the sabbatical year, for it began with the seventh month) the whole law was read in the hearing of the people. The law of the sabbatical year was habitually broken by the Jews for a long period before the Babylonian exile. The 70 years of exile and the land's desolation were regarded as making up for the unobserved Sabbaths of the land (2 Chronicles 36:21).

From the LDS BIBLE DICTIONARY: - Year of Jubilee:
A name given to every fiftieth year. It got its name from the fact that the beginning of the year was announced by the blowing of a trumpet on the Day of Atonement. In it land that had changed hands, except in non-Levitical walled cities, reverted to the family to which it had belonged at the original settlement, and all bondmen of Israelitish birth were set free (Leviticus 25:8-16, 23-55; 27:16-25). We have no record in the Old Testment of the observance of any year of jubilee, but the prophets allude to it in various passages.

 

Leviticus 25:1-22:  And the LORD spake 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 LORD. Six years thou shalt sow thy field, and six years thou shalt prune thy vineyard, and gather in the fruit thereof; But in the seventh year shall be a sabbath of rest unto the land, a sabbath for the LORD: thou shalt neither sow thy field, nor prune thy vineyard. That which groweth of its own accord of thy harvest thou shalt not reap, neither gather the grapes of thy vine undressed: for it is a year of rest unto the land. And the sabbath of the land shall be meat for you; for thee, and for thy servant, and for thy maid, and for thy hired servant, and for thy stranger that sojourneth with thee, And for thy cattle, and for the beast that are in thy land, shall all the increase thereof be meat.
           And thou shalt number seven sabbaths of years unto thee, seven times seven years; and the space of the seven sabbaths of years shall be unto thee forty and nine years. Then shalt thou cause the trumpet of the jubile to sound on the tenth day of the seventh month, in the day of atonement shall ye make the trumpet sound throughout all your land. And ye shall hallow the fiftieth year, and proclaim liberty throughout all the land unto all the inhabitants thereof: it shall be a jubile unto you; and ye shall return every man unto his possession, and ye shall return every man unto his family. A jubile shall that fiftieth year be unto you: ye shall not sow, neither reap that which groweth of itself in it, nor gather the grapes in it of thy vine undressed. For it is the jubile; it shall be holy unto you: ye shall eat the increase thereof out of the field. In the year of this jubile ye shall return every man unto his possession. And if thou sell ought unto thy neighbour, or buyest ought of thy neighbour's hand, ye shall not oppress one another: According to the number of years after the jubile thou shalt buy of thy neighbour, and according unto the number of years of the fruits he shall sell unto thee: According to the multitude of years thou shalt increase the price thereof, and according to the fewness of years thou shalt diminish the price of it: for according to the number of the years of the fruits doth he sell unto thee. Ye shall not therefore oppress one another; but thou shalt fear thy God: for I am the LORD your God. Wherefore ye shall do my statutes, and keep my judgments, and do them; and ye shall dwell in the land in safety. And the land shall yield her fruit, and ye shall eat your fill, and dwell therein in safety. And if ye shall say, What shall we eat the seventh year? behold, we shall not sow, nor gather in our increase: Then I will command my blessing upon you in the sixth year, and it shall bring forth fruit for three years. And ye shall sow the eighth year, and eat yet of old fruit until the ninth year; until her fruits come in ye shall eat of the old store.

Deuteronomy 15:1-18: At the end of every seven years thou shalt make a release. And this is the manner of the release: Every creditor that lendeth ought unto his neighbour shall release it; he shall not exact it of his neighbour, or of his brother; because it is called the LORD'S release. Of a foreigner thou mayest exact it again: but that which is thine with thy brother thine hand shall release; Save when there shall be no poor among you; for the LORD shall greatly bless thee in the land which the LORD thy God giveth thee for an inheritance to possess it: Only if thou carefully hearken unto the voice of the LORD thy God, to observe to do all these commandments which I command thee this day. For the LORD thy God blesseth thee, as he promised thee: and thou shalt lend unto many nations, but thou shalt not borrow; and thou shalt reign over many nations, but they shall not reign over thee. If there be among you a poor man of one of thy brethren within any of thy gates in thy land which the LORD thy God giveth thee, thou shalt not harden thine heart, nor shut thine hand from thy poor brother: But thou shalt open thine hand wide unto him, and shalt surely lend him sufficient for his need, in that which he wanteth. Beware that there be not a thought in thy wicked heart, saying, The seventh year, the year of release, is at hand; and thine eye be evil against thy poor brother, and thou givest him nought; and he cry unto the LORD against thee, and it be sin unto thee. Thou shalt surely give him, and thine heart shall not be grieved when thou givest unto him: because that for this thing the LORD thy God shall bless thee in all thy works, and in all that thou puttest thine hand unto. For the poor shall never cease out of the land: therefore I command thee, saying, Thou shalt open thine hand wide unto thy brother, to thy poor, and to thy needy, in thy land.
           And if thy brother, an Hebrew man, or an Hebrew woman, be sold unto thee, and serve thee six years; then in the seventh year thou shalt let him go free from thee. And when thou sendest him out free from thee, thou shalt not let him go away empty: Thou shalt furnish him liberally out of thy flock, and out of thy floor, and out of thy winepress: of that wherewith the LORD thy God hath blessed thee thou shalt give unto him. And thou shalt remember that thou wast a bondman in the land of Egypt, and the LORD thy God redeemed thee: therefore I command thee this thing to day. And it shall be, if he say unto thee, I will not go away from thee; because he loveth thee and thine house, because he is well with thee; Then thou shalt take an aul, and thrust it through his ear unto the door, and he shall be thy servant for ever. And also unto thy maidservant thou shalt do likewise. It shall not seem hard unto thee, when thou sendest him away free from thee; for he hath been worth a double hired servant to thee, in serving thee six years: and the LORD thy God shall bless thee in all that thou doest.