Was it against the Mosaic Law for Boaz to marry Ruth, according to Deuteronomy 23:3?

Ruth, the Moabitess, who as a heathen could not have any right amidst the people of God (according to the law) takes refuge with the God of Israel and is received into His people by His grace. By her marriage with Boaz the redeemer (hebr. go'el) she receives a place in King David's genealogy and by it also in the Messiah's (Jesus of Nazareth) genealogy (Ruth 4:22; Mat. 1:5).

Ruth especially was disqualified by the law of Jehovah, for she was under its ban which rested specifically upon the whole of her people. She belonged to "the children of Lot," and she bore the stigma of the incestuous origin of that race. Her birth excluded her from the worshippers of Jehovah in Shiloh. Her marriage with Mahlon, the second son of Elimelech, did not remove nor lessen her disqualification, for by the ordinance of Moses the marriage was illegal. The instructions relevant to her case were to be valid "for ever" (Deut. 23:3-6). Ruth, therefore, was permanently barred by birth from entering "the congregation of Jehovah," the circle of His special earthly blessing.

Thus the Moabitess was under the condemnation of the law of Jehovah. Nevertheless, though He could not righteously receive her according to His own law, He graciously accepted her according to His own mercy; and according to the riches of His coming glory by Christ Jesus He also gave her an honourable place in the royal archives of the Son of God Who as to the flesh came at the appointed time of the seed of her great-grandson, David (Rom. 1:2-4).

Boaz then addressed the elders and all the people present, declaring them as witnesses that he had bought all that had previously belonged to Elimelech and his two sons (v. 9). But more than that, he had acquired Ruth the Moabitess as his wife, to perpetuate the name of the dead (Elimelech and his sons), since Ruth had had no children by her husband, Chilion (v. 10). In this way the law of Israel was perfectly kept, and Ruth, though a Moabitess, was welcomed into the commonwealth of Israel in spite of the law that forbade the acceptance of a Moabite to the tenth generation. For Israel's law had made provision for a related redeemer to accomplish such a reception. Just so, the ungodly Gentiles were excluded from Israel by law, but the law still bore witness of the coming of the Lord Jesus, whose great sacrifice has brought redemption for the ungodly, so that Gentile believers today are united to Christ in a bond that is pictured by marriage (2 Cor.11:2).

But we have not yet got at that which gives fullest significance to this name in the genealogy. Against this Ruth, with all her loveliness and with all her goodness, there was lying a ban which did not lie in the same way against the others. She was a Moabitess, and against these there had been leveled an express statute of the law. "An Ammonite or a Moabite shall not enter into the congregation of the Lord, even unto their tenth generation they shall not enter into the congregation of the Lord forever." (Deut. 23:3.) Thus Ruth lay under the interdict of the law. It is striking that it was to this devoted, to this lovely woman that the law applied, — not to Rahab nor even to Tamar; God having thus proclaimed in an unmistakable way the law's character; not bringing it in to condemn the sinner and the harlot, (where men's minds would have done so,) but introducing it as that which would have excluded a Ruth, even with her piety. Emphatically was it thus taught that it was man as man that was shut out from God; — not in his sins merely, but in his righteousness; and that if we stand on that ground all "our righteousnesses are as filthy rags."

But the law does not keep Ruth out. Moabitess as she is, she does enter into the congregation of the Lord. The law is set aside in her behalf, and instead of her descendants being excluded to the tenth generation, her child of the third generation sits upon Israel's throne, and hears the promise which confirms that throne to his heirs for succeeding generations.

But we have not yet got at that which gives fullest significance to this name in the genealogy. Against this Ruth, with all her loveliness and with all her goodness, there was lying a ban which did not lie in the same way against the others. She was a Moabitess, and against these there had been levelled an express statute of the law. "An Ammonite or a Moabite shall not enter into the congregation of the Lord, even unto their tenth generation they shall not enter into the congregation of the Lord for ever" (Deut. 23:3). Thus Ruth lay under the interdict of the law. It is striking that it was to this devoted, to this lovely woman that the law applied, not to Rahab nor even to Tamar; God having thus proclaimed in an unmistakable way the law's character; not bringing it in to condemn the sinner and the harlot (where men's minds would have done so), but introducing it as that which would have excluded a Ruth, even with her piety. Emphatically was it thus taught that it was man as man that was shut out from God; not in his sins merely, but in his righteousness; and that if we stand on that ground all "our righteousnesses are as filthy rags."

But the law does not keep Ruth out. Moabitess as she is, she does enter into the congregation of the Lord. The law is set aside in her behalf, and instead of her descendants being excluded to the tenth generation, her child of the third generation sits upon Israel's throne, and hears the promise which confirms that throne to his heirs for succeeding generations.

“Then she fell on her face, and bowed herself to the ground, and said unto him, Why have I found grace in thine eyes, that thou shouldest take knowledge of me, seeing I am a stranger?” Grace always humbles us. Mephibosheth in the presence of the grace of David, says, “What is thy servant that thou shouldst look upon, such a dead dog as I am?” Ruth confesses she was but “a stranger.” But there was a vast deal more than this, though she herself may not have known it. The law of Moses said, “An Ammonite or a Moabite shall not enter into the congregation of the Lord, even to their tenth generation shall they not enter into the congregation of the Lord forever.” It said further, “Thou shalt not seek their peace nor their prosperity all thy days forever” (Deut. 23:3,6). What then could she have expected from Boaz but to be rebuked and driven from his field? And that same stern law, that cursed and shut out the Moabites from blessing, curses and shuts up heaven against us all. “Cursed,” it thunders, “is every one that continues not in all things which are written in the book of the law to do them.” But, thank God, if the law “given by Moses” condemns the sinner, “grace and truth” which “came by Jesus Christ” saves him when he trusts that gracious Saviour. The same saving faith which wrought in Rahab the harlot, was found in Ruth. Boaz says, “The Lord God of Israel, under whose wings thou art come to trust.” Though by nature a cursed Moabite, her faith had saved her; though condemned by the law, she was justified by faith. And you, my unconverted hearer, though by nature a child of wrath and cursed by the law you have broken, may put your trust in Christ tonight, and thus be saved. “By grace are ye saved through faith,” is the testimony of Scripture (Eph. 2:8).

Ruth, the third woman mentioned, is an exception, for there is no stain upon her character. She was a Moabitess. The law was against her and cursed her. It is written, "An Ammonite or Moabite shall not enter into the congregation of the Lord; even to their tenth generation shall they not enter into the congregation of the Lord forever" (Deut. 23:3). But in faith too she enters into the congregation with her children, and the third after her, her grandson, is King David himself. The law which had pronounced the curse is completely set aside in her case.

Ques.—How can we reconcile the command in Deut.23:3 with the free reception of Ruth the Moabitess in Israel when she came with Naomi? And her reception seems pleasing to God, who even gives her a place in the genealogy of Christ (Matt.1:5).

The law, even with the most merciful construction, could no longer interpose. "An Ammonite or Moabite shall not enter into the congregation of the Lord; even to their tenth generation shall they not enter into the congregation of the Lord forever" (Deut. 23:3). The apostate people had deliberately given up all claim, and so far as the law was concerned, were cut off.

The children of the captivity had already separated themselves from all foreigners (Neh. 9:2) and the peoples of the lands (Neh. 10:28), but until that day they had not taken account of this mixed multitude, whose presence was familiar to them. But now they realized that the word of God named them specifically, and they had not paid attention to this! Indeed, Deuteronomy 23:3-6 said: "An Ammonite or Moabite shall not come into the congregation of Jehovah; even their tenth generation shall not come into the congregation of Jehovah for ever; because they met you not with bread and with water on the way, when ye came forth out of Egypt, and because they hired against thee Balaam the son of Beor, of Pethor of Mesopotamia, to curse thee. But Jehovah thy God would not listen to Balaam; and Jehovah thy God turned the curse into blessing unto thee, because Jehovah thy God loved thee. Thou shalt not seek their peace nor their prosperity all thy days for ever".

These events had taken place approximately one thousand years previously, and it is very important to remark that the time elapsed in the meanwhile in absolutely no way diminished the guilt of Ammon and Moab. God's sentence against them remained standing, because God does not change, and because a thousand years are as one day to Him. We often think that, as in human affairs, that a sin committed in the past against Christ and against the people of God, is simply dismissed. Why recall these things we ask? They happened so long ago, that no one remembers them. Therefore, can we still take account of them? Such reasoning always finds approval from what is pleasing in our sinful nature. The idea of wiping over the evil with a damp sponge seems very recommendable to us at first view; but we forget that the question must be considered from God's point of view. What does He think of the injury made against Himself and His people? The fact is that, from the beginning, He had pronounced a final sentence against "the mixed multitude" and, in this case, Israel was not to consider what seemed suitable to them, but rather what God thought of the dishonor inflicted against His Name. Time had not changed the sin of Moab and Ammon, nor the obligation to separate from them. As for the foreigners and the people of the land, and all who inhabited Canaan at the time of conquest, Deuteronomy had ordered, not only to destroy them entirely, to make no alliance with them, to show them no grace, but beyond that to refrain from joining them through the ties of marriage, lest they lead the people into idolatry (Deut. 7:1-4). Now such was not the case here concerning Ammon and Moab, and as for profane marriages, the people had already condemned them in Ezra 10 and had purified themselves from them. It was rather a case of not considering these two peoples as forming part of the congregation of the Lord.