Ruth 3:3

“ Wash yourself therefore, and anoint yourself, and put your clothes on you, and get you down to the threshing-floor, but do not make yourself known to the man, until he has done eating and drinking.”

Ruth was therefore to wash herself, and anoint herself with oil, and then dress and go down to the threshingfloor. There she must wait patiently and unobserved until Boaz had finished eating and drinking. As mentioned above this eating and drinking would probably be part of the celebrations because the harvest had been safely gathered in. It was not to be interrupted. What Ruth was about to do must not be done publicly.