Verse 13: Tarry this night, and it shall be in the morning, that if he will (Deut. 25:5; Ruth 4:5; Matt. 22:24) perform unto thee the part of a kinsman, well; let him do the kinsman’s part: but if he will not do the part of a kinsman to thee, then will I do the part of a kinsman to thee, (Judg. 8:19; Jer. 4:2) as the LORD liveth: lie down until the morning.
[If he be willing…all is well, אִם־יִגְאָלֵ֥ךְ טוֹב֙ יִגְאָ֔ל] If he would redeem thee, good (or, well [Junius and Tremellius, Munster, Tigurinus, English], it is well [Pagnine]); let him redeem (Septuagint), or, let him avenge (Junius and Tremellius), let him play the part (Tigurinus, English). Now, this is called redeeming, because they were redeeming together the inheritance left behind by a brother. Certain Hebrews thus: If Tob would redeem thee, let him certainly redeem; so that Tob might be the proper name of that protector. But certainly, if this was his name, why does Boaz thus address him, Turn aside, such a one? Thence it appears that the writer of this history either was altogether ignorant of the name of this man, or was unwilling to publish it for some reason (Drusius).
If he will perform unto thee the part of a kinsman, that is, take thee to wife, to raise up seed to his brother, as he ought to do.
[I will take thee, etc.] Admire here the eminent charity, and also chastity, of Boaz, inasmuch as he was unwilling to touch Ruth, lying at his feet, but he premised marriage. Moreover, the hardness of the pallet and the cold much helped Boaz’s chastity; that is, because he was reclining, not on a feathery bed, but in the air under heaven. Hence the Pharisees, when reclining, were applying a sheet of lead to their kidneys (in which is the source of seed), to cool them, and thus to avoid nocturnal pollutions in sleep (Lapide).
Verse 14: And she lay at his feet until the morning: and she rose up before one could know another. And he said, (Rom. 12:17; 14:16; 1 Cor. 10:32; 2 Cor. 8:21; 1 Thess. 5:22) Let it not be known that a woman came into the floor.
Before one could know another, that is, while it was yet so dark that one person could not discern another. Or, before one did know the other, that is, before they were carnally known to one another.
[Take care that no one know] So that he might look to their honor and reputations, and so also prevent scandal (Bonfrerius).
Let it not be known that a woman came into the floor; he takes care to preserve not only his conscience towards God, but his reputation, and hers also, among men.
 Hebrew: לִ֣ינִי׀ הַלַּ֗יְלָה וְהָיָ֤ה בַבֹּ֙קֶר֙ אִם־יִגְאָלֵ֥ךְ טוֹב֙ יִגְאָ֔ל וְאִם־לֹ֙א יַחְפֹּ֧ץ לְגָֽאֳלֵ֛ךְ וּגְאַלְתִּ֥יךְ אָנֹ֖כִי חַי־יְהוָ֑ה שִׁכְבִ֖י עַד־הַבֹּֽקֶר׃
 Hebrew: וַתִּשְׁכַּ֤ב מַרְגְּלֹתָו֙ עַד־הַבֹּ֔קֶר וַתָּ֕קָם בִּטְ֛רוֹם יַכִּ֥יר אִ֖ישׁ אֶת־רֵעֵ֑הוּ וַ֙יֹּאמֶר֙ אַל־יִוָּדַ֔ע כִּי־בָ֥אָה הָאִשָּׁ֖ה הַגֹּֽרֶן׃