Original Verse:
Ezra Chapter 7 Verse 24Also we certify you, that touching any of the priests and Levites, singers, porters, Nethinims, or ministers of this house of God, it shall not be lawful to impose toll, tribute, or custom, upon them.

Reference Verses:
Ezra Chapter 7 Verse 7And there went up some of the children of Israel, and of the priests, and the Levites, and the singers, and the porters, and the Nethinims, unto Jerusalem, in the seventh year of Artaxerxes the king.
Genesis Chapter 47 Verse 22Only the land of the priests bought he not; for the priests had a portion assigned them of Pharaoh, and did eat their portion which Pharaoh gave them: wherefore they sold not their lands.
Ezra Chapter 4 Verse 13Be it known now unto the king, that, if this city be builded, and the walls set up again, then will they not pay toll, tribute, and custom, and so thou shalt endamage the revenue of the kings.