Jamieson, Fausset and Brown on Ezra 8:21

Ezr 8:21-36. A Fast Proclaimed.

21. Then I proclaimed a fast there--The dangers to travelling caravans from the Bedouin Arabs that prowl through the desert were in ancient times as great as they still are; and it seems that travellers usually sought the protection of a military escort. But Ezra had spoken so much to the king of the sufficiency of the divine care of His people that he would have blushed to apply for a guard of soldiers. Therefore he resolved that his followers should, by a solemn act of fasting and prayer, commit themselves to the Keeper of Israel. Their faith, considering the many and constant perils of a journey across the Bedouin regions, must have been great, and it was rewarded by the enjoyment of perfect safety during the whole way.