I venture to think that this precept had in it somewhat more, than merely what is contained in the obvious letter of it. If it be remembered, that the promise of the woman's seed, bruising the serpent's head, had not in those early ages been so clearly and fully revealed, in what stock or tribe the promised seed should spring, this will serve to show, why it was that the whole nation of the Jews were so very anxious to have children. And, therefore, the preserving the name in Israel was principally with this view. But if we turn to the example of Boaz, in the case of Ruth, where this precept was fully carried into effect, and read what the HOLY GHOST hath been pleased to record concerning this thing: and if we do not forget, at the same time, that Boaz after the flesh, was a progenitor of the LORD JESUS CHRIST; the subject will then open to our view in all its glory. See Ruth 3:9, to the end, and Ruth 4:1 throughout. Blessed JESUS! thou art indeed our near kinsman, our GOD-Redeemer! and thou hast not only married our nature, but hast redeemed our mortgaged inheritance, when all other brethren were incompetent to do it.
Deuteronomy 25:5-10
5 If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry without unto a stranger: her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of an husband's brother unto her.
6 And it shall be, that the firstborn which she beareth shall succeed in the name of his brother which is dead, that his name be not put out of Israel.
7 And if the man like not to take his brother's wife, then let his brother's wife go up to the gate unto the elders, and say, My husband's brother refuseth to raise up unto his brother a name in Israel, he will not perform the duty of my husband's brother.
8 Then the elders of his city shall call him, and speak unto him: and if he stand to it, and say, I like not to take her;
9 Then shall his brother's wife come unto him in the presence of the elders, and loose his shoe from off his foot, and spit in his face, and shall answer and say, So shall it be done unto that man that will not build up his brother's house.
10 And his name shall be called in Israel, The house of him that hath his shoe loosed.