Albert Barnes Commentary Ruth 3:2

"And now is not Boaz our kinsman, with whose maidens thou wast? Behold, he winnoweth barley to-night in the threshing-floor." — Ruth 3:2 (ASV)

Behold, he winnoweth barley ... - The simple manners of Boaz and his times are here before us. This “mighty man of wealth” assists personally in the winnowing of his barley, which lies in a great heap on the floor (Ruth 3:15), and sleeps in the open threshing-floor to protect his grain from depredation.

Tonight - For the sake of the breeze which springs up at sunset, and greatly facilitates the “cleansing” (separation) of the grain tossed up across the wind.