And she lay at his feet until the morning: and she rose up before one could know another. And he said, Let it not be known that a woman came into the floor. (Ruth 3:14)
Literally, “the woman.” Probably influenced by the use of the definite article, and considering it unlikely that Boaz was sleeping alone that night near the threshing floor, the Talmud considers that the command must have been addressed to some of the reapers who remained with him in the field. It would have been most unpleasant for all concerned should any suspicion attach to his relationship to Ruth.
Let it not be known.
Not only for propriety’s sake, but also to safeguard the plan of Boaz to complete arrangements with the nearer kinsman. Should he learn of the events of the preceding night, he might refuse to relinquish his prior rights.
Before one could know.
At the very first light of dawn, before the arrival of the harvesters and the gleaners. The few who would be about would be unable to recognize Ruth anyway.