Was to be celebrated among the Jews once every seven years; the land was to rest, and be left without culture, Exodus 23:10,11 Leviticus 25:17. God appointed the observance of the Sabbatical year, to preserve the remembrance of the creation of the world; to enforce the acknowledgment of his sovereign authority over all things, particularly over the land of Canaan, which he had given to the Hebrews; and to inculcate humanity on his people, by commanding that they should resign to servants, to the poor, to strangers and to brutes, the produce of the fields, of their vineyards, and of their gardens. Josephus and Tacitus both mention the Sabbatical year as existing in their day. See JUBILEE.
Source: ATS 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; Compare 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).
Source: Easton's Bible Dictionary
Sabbatical year
Each seventh year, by the Mosaic code, was to be kept holy. (Exodus 23:10,11) The commandment is to sow and reap for six years, and to let the land rest on the seventh, "that the poor of thy people may eat; and what they leave the beasts of the held shall eat. It is added in ( 15:1) ... that the seventh Year should also be one of release to debtors. ( 15:1-11) Neither tillage nor cultivation of any sort was to be practiced. The sabbatical year opened in the sabbatical month, and the whole law was to be read every such year, during the feast of Tabernacles, to the assembled people. At the completion of a week of sabbatical years, the sabbatical scale received its completion in the year of jubilee. [JUBILEE] The constant neglect of this law from the very first was one of the national sins that were punished by the Babylonian captivity. Of the observance of the sabbatical year after the captivity we have a proof in 1 Macc. 6:49.