At midnight, Boaz was startled, turned over, and there lying at his feet was a woman!
Here is, I. Boaz's good management of his common affairs. It is probable, according to the common usage, 1. When his servants winnowed, he was with them, and had his eye upon them, to prevent, not their stealing any of his corn (he had no reason to fear that), but their waste of it through carelessness in the winnowing of it.
Commenting on Ruth 3:6-13
And it came to pass at midnight,.... So long Boaz slept without knowledge of any person being at his feet, and so long Ruth had lain there; but awaking, and perceiving something at his feet, which pressed them, it made him look about and feel, and so affected him: that the man was afraid; though a man, and a man of spirit, he was afraid...
The man was afraid, and turned himself - The verb ילפת yillapheth, which we render he turned himself, has puzzled even the Targumist, who translates the clause thus: "The man trembled, and his flesh became like a (boiled) turnip through fear." It is fully evident Boaz had no intimation of the present proceedings.