Jamieson, Fausset and Brown on Judges 6:11

Jud 6:11-16. An Angel Sends Gideon to Deliver Them.

11. there came an angel of the Lord--He appeared in the character and equipments of a traveller (Jud 6:21), who sat down in the shade to enjoy a little refreshment and repose. Entering into conversation on the engrossing topic of the times, the grievous oppression of the Midianites, he began urging Gideon to exert his well-known prowess on behalf of his country. Gideon, in replying, addresses him at first in a style equivalent (in Hebrew) to "sir," but afterwards gives to him the name usually applied to God.

an oak--Hebrew, "the oak"--as famous in after-times.

Ophrah--a city in the tribe of Manasseh, about sixteen miles north of Jericho, in the district belonging to the family of Abiezer (Jos 17:2).

his son Gideon threshed wheat by the wine-press--This incident tells emphatically the tale of public distress. The small quantity of grain he was threshing, indicated by his using a flail instead of the customary treading of cattle--the unusual place, near a wine-press, under a tree, and on the bare ground, not a wooden floor, for the prevention of noise--all these circumstances reveal the extreme dread in which the people were living.