When Boaz had eaten and drunk - The Targum adds, "He blessed the name of the Lord, who had heard his prayer, and removed famine from the land of Israel."
Went to lie down - As the threshing-floors of the Eastern nations are in general in the open air, it is very likely that the owner or some confidential person continued in the fields till the grain was secured, having a tent in the place where the corn was threshed and winnowed. Boaz seems to have acted thus.