Nehemiah 10:28-31

28Now the rest of the people—the priests, the Levites, the gatekeepers, the singers, the temple servants, and all those who had separated themselves from the peoples of the lands to the Law of God, their wives, their sons, their daughters, all those who had knowledge and understanding—

29are joining with their fellow Israelites, their nobles, and are taking on themselves a curse and an oath to walk in God’s Law, which was given through Moses the servant of God, and to keep and to observe all the commandments of God our Lord, and His ordinances and statutes:

30and that we will not give our daughters [as wives] to the peoples of the land or take their daughters for our sons.

31As for the peoples of the land who bring merchandise or any grain on the Sabbath day to sell, we will not buy from them on the Sabbath or on a holy day; and we will give up raising crops during the seventh year [leaving the land uncultivated], and forgive every debt.