Lo, we heard of it at Ephratah. "It" is probably "the ark"—not yet mentioned, but a main object of the writer's thoughts; and "Ephratah" is the district south and west of Jerusalem, in which both Bethlehem and Kirjath-jearim were situated.
And found it in the fields of the wood; rather, in the fields of Jaar. "Jaar" is a contracted and poetic name for Kirjath-jearim, where the ark remained from its return out of the country of the Philistines till David transferred it to Jerusalem (1 Chronicles 13:5-13).