Nehemiah 13:3

Now it came to pass, when they had heard the law, that they separated from Israel all the mixed multitude.

Hearing the law moved Israel to immediate obedience, putting into practice what they had heard and publicly pledged to keep by separating away forbidden foreigners from the congregation. The law they had heard was the Mosaic statute that permanently barred Ammonites and Moabites from the assembly because of their cruelty and treachery toward Israel. Tobiah the Ammonite belonged to that proscribed race and stood as an enemy of God and His truth, so lodging him in a temple storeroom that had been emptied of tithes and offerings was open defiance of that word and contempt for God.

Nehemiah carried out the required separation by casting all of Tobiah's household goods out of the chamber. He then had the chambers cleansed and brought back the vessels of the house of God with the meat offering and the frankincense.