Nehemiah 10:28-31

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

29join with their brothers, their nobles, and enter into a curse and an oath to walk in God's Law that was given by Moses the servant of God, and to observe and do all the commandments of the Lord our Lord and his rules and his statutes.

30We will not give our daughters to the peoples of the land or take their daughters for our sons.

31And if the peoples of the land bring in goods 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 forego the crops of the seventh year and the exaction of every debt.