Nehemiah 2:7. Moreover I said unto the king, If it please the king, let letters be given me to the governors beyond the river, that they may convey me over till I come into Judah.
It is still customary in many parts of the East to obtain letters of recommendation, or orders for safe conduct, when the traveler desires to visit different districts under one central authority. Without these he could not travel in comfort or safety; but having them, those to whom he presents them are bound to protect him. Thus Nehemiah was able to travel safely throughout the Persian empire.