Deuteronomy 23:3
An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth generation shall they not enter into the congregation of the LORD for ever: An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth generation shall they not enter into the congregation of the LORD for ever:
The Ammonites and Moabites were barred from entering the assembly of the Lord, with the ban extending even to the tenth generation and continuing forever. This lasting exclusion was imposed because of their cruelty and treachery toward Israel. Tobiah was an Ammonite and an enemy of Israel, and as such he belonged to a people shut out by this command. To set apart a room for him within the temple therefore stood in direct defiance of the word of God.