What rider spurs him from the darkening east

What rider spurs him from the darkening east
As from a forest, and with rapid pound
Of hooves, now light, now louder on hard ground,
Approaches, and rides past with speed increased,
Dark spots and flecks of foam upon his beast?
What shouts he from the saddle, turning ’round,
As he rides on?—”Greetings!—I made the sound;
“Greetings from Nineveh!”—it seemed, at least.
Did someone catch the object that he flung?
He held some object in his saddle-bow,
And flung it towards us as he passed; among
The children then it fell most likely; no,
‘Tis here: a little bell without a tongue.
Listen; it has a faint voice even so.