So she went down to the threshing floor and did just as her mother-in-law had commanded her. And when Boaz had eaten and drunk, and his heart was merry, he went to lie down at the end of the heap of grain. Then she came softly and uncovered his feet and lay down. At midnight the man was startled and turned over, and behold, a woman lay at his feet! He said, “Who are you?” And she answered, “I am Ruth, your servant. Spread your wings over your servant, for you are a redeemer.” And he said, “May you be blessed by the LORD, my daughter. You have made this last kindness greater than the first in that you have not gone after young men, whether poor or rich. And now, my daughter, do not fear. I will do for you all that you ask, for all my fellow townsmen know that you are a worthy woman. And now it is true that I am a redeemer. Yet there is a redeemer nearer than I. Remain tonight, and in the morning, if he will redeem you, good; let him do it. But if he is not willing to redeem you, then, as the LORD lives, I will redeem you. Lie down until the morning.” (Ruth 3:6-13)
What in one age or nation would be improper, is not always so in another age or another nation. Being a judge of Israel, Boaz would tell Ruth what she should do; also whether he had the right of redemption, and what methods must be taken, and what rites used, in order to accomplishing her marriage with him or another person.
The conduct of Boaz calls for the highest praise. He attempted not to take advantage of Ruth; he did not disdain her as a poor, destitute stranger, nor suspect her of any ill intentions. He spoke honorably of her as a virtuous woman, made her a promise, and as soon as the morning arrived, sent her away with a present to her mother-in-law.
Boaz made his promise conditional, for there was a kinsman nearer than he, to whom the right of redemption belonged.
Adapted from Matthew Henry Concise Commentary