Verse 14: If ye will (Josh. 24:14; Ps. 81:13, 14) fear the LORD, and serve him, and obey his voice, and not rebel against the commandment (Heb. mouth) of the LORD, then shall both ye and also the king that reigneth over you continue following (Heb. be after) the LORD your God…
[If ye will fear the Lord, etc.] This is no vain repetition of words. But either, after the manner of scripture, when a matter of great moment is expressed, it expresses it in multiple expressions signifying the same thing; so that greater effort, fervor, and zeal might be signified. See similar things in Leviticus 26:3; Deuteronomy 28:1, etc.; Psalm 89:30, 31. See also John 1:20. Or rather the individual terms have diverse significations. If ye will fear, etc. He begins from the fear of the Lord, as from the first degree of perfection. He adds, and will serve Him. That inward fear is not sufficient, unless external acts of obedience arise from it (Mendoza).
[And will not exasperate the mouth of the Lord (thus Pagnine),וְלֹ֥א תַמְר֖וּ אֶת־פִּ֣י יְהוָ֑ה] And will not irritate the mouth of the Lord (Montanus). The mouth of the Lord is exasperated, when it is provoked to wrath; for those that are angry exasperate, make rough, their face, and put on a gloomy and threatening expression (Menochius, similarly Lapide). To exasperate is to render a gentle and forgiving nature difficult and severe; or to bring anyone to that point of fury, that they vomit out words threatening and full of outrage. For this is to exasperate the mouth (Sanchez). Or the mouth of the Lord is taken for the laws and precepts that He emitted from His mouth; that is to say, if ye will not transgress the law, and provoke it, as it were, to anger. It is personification, whereby a soul, sense and anger, are attributed to the law. But by the law is understood God the lawgiver (Lapide). And will not rebel against the mouth (the word [Vatablus, thus Munster, Jonathan], commandments [Piscator, similarly Junius and Tremellius, Castalio]) of Jehovah (Tigurinus, Vatablus, Jonathan, similarly the Septuagint). A Metonymy of the efficient, and a Synecdoche of genus. Mouth in the place of speech, and speech in the place of commandment (Piscator). And will not provoke Him to anger (Syriac, Arabic). And will not change the mouth, etc. See on Numbers 27:14 (Malvenda). Will have made the mouth of the Lord bitter (Lapide). It is anthropopathia, taken from that bitterness which often arises in man scattered abroad. For, when they see themselves despised, bile is excited and the mouth is made bitter (Martyr).
[Ye, both ye and your king, shall be…following the Lord,וִהְיִתֶ֣ם גַּם־אַתֶּ֗ם וְגַם־הַמֶּ֙לֶךְ֙—אַחַ֖ר יְהוָ֥ה] And shall be both ye and your king…after the Lord (Pagnine, similarly Montanus, Tigurinus, Dutch, Mariana). Or, walking after the Lord (Septuagint). After the worship of the Lord (Jonathan). Ye shall remain…following the Lord (Syriac). Ye shall walk, ye and your king…in the obedience of the Lord (Arabic). He shows that from the virtue of the people the virtue of the King is to be confirmed beyond all doubt, and to be increased (Mendoza). Long shall ye continue, or ye shall live for a long time, after Jehovah; that is, in the worship of Jehovah. The ו/and in וִהְיִתֶם, and ye shall be, is not a copula, but converts the perfect into the future/imperfect (Vatablus). Ye shall certainly continue…following Jehovah (Junius and Tremellius, similarly the English), walking after Jehovah (Piscator). This passage is variously explained: either thus; Ye shall walk after the Lord, so that ye might be unwilling to go before Him. For those that follow the traditions of men and their own inventions run ahead of the Lord, and in a certain way prescribe to Him. Or thus; Ye shall be safe and flourishing: the Lord shall defend you (Martyr). Ye shall subsist; for a long time ye shall live and thrive (Malvenda). That is to say, God shall be your king, as previously; and, after the manner of a captain, He shall go before you, and ye shall live securely under His guardianship (Menochius out of Sanchez). Even if ye have sinned grievously, by asking for a king, and have deserted and scorned God, your king, as if no longer suitable for governing; nevertheless, if ye should live piously, the Lord shall not desert you; but He shall be a guide and protector to the king, and to you, so that you might live happily under His rule. For, when we earnestly repent, even those things that were ill and illegitimately undertaken, that is, if they are not sins of themselves, are able to obtain a favorable outcome (Osiander). Others: ye shall be following the Lord; that is to say, ye shall show that with the whole heart ye are following the Lord, as sons a father, as subjects a king. Which shall be to you great glory, and a great reward. For God shall protect and prosper you as His own worshippers (Lapide). To be after the Lord is to follow after Him (Drusius).
Then shall…ye…continue following the LORD: Hebrew, Then shall…ye…be (that is, walk, or go) after the Lord, that is, God shall still go before you, as he hath hitherto done, as your Leader or Governor, to direct, protect, and deliver you; and he will not forsake you, as you have given him just cause to do. Sometimes this phrase of going after the Lord signifies a man’s obedience to God; but here it is otherwise to be understood; (as it is no new thing for the same phrase in several places to be understood in quite different senses;) and it notes not a duty to be performed, but a promise of a privilege to be received upon the performance of their duty, because it is opposed to a threatening denounced in case of disobedience in the next verse.
Verse 15: But if ye will (Lev. 26:14, 15, etc.; Deut. 28:15, etc.; Josh. 24:20) not obey the voice of the LORD, but rebel against the commandment of the LORD, then shall the hand of the LORD be against you, (1 Sam. 12:9) as it was against your fathers.
[The hand of the Lord shall be upon you, and upon your fathers,בָּכֶ֖ם וּבַאֲבֹתֵיכֶֽם׃] On you, and on your fathers (Munster, Tigurinus, Montanus). Deceased parents are punished in their children (Martyr); at least with infamy (Mariana). For children are in a certain way parts of their parents. Others explain it in this way, that the promises made to the fathers are not going to have place in the case of the children (Martyr). And against your fathers, that is, your paternal houses, or families (certain interpreters in the Dutch). Others: on or against you, as against your fathers (Pagnine, Jonathan, Syriac, Arabic, Mariana, Dutch, English, Junius and Tremellius, Vatablus, Drusius). ו/and here is set down in the place of as (Vatablus, Glassius). Whenever the ו has a signification of comparison, thus, as, is called Waw הַשְּׁיָאָה, of adequation. Thus in Proverbs 10:25, as the whirlwind passeth,וְאֵין, so is not (or perisheth), the wicked. Thus in Proverbs 17:3; 25:23; etc.; Isaiah 53:7, as a sheep… וְלֹא, so not, openeth he his mouth, Acts 8:32. See Amos 9:7. Thus in Matthew 6:10, as in heaven as in earth, that is, so in earth. See also Acts 7:51; John 20:21 (Glassius’ “Grammar” 690, 691). Others thus upon you and upon your king (Septuagint, Castalio). Against your fathers; that is, against your kings, who ought to be as fathers to children (Hebrews in Vatablus). For a Prince is the Father of his country, Aristotle’s Ethics 8:11. Gentiles were calling their Kings fathers. Agamemnon is the father and shepherd of the peoples to Homer (Lapide). Hence Æneas is a father to Virgil. And Augustus is called pater patriæ, the father of the country, by the Senate. Moreover, reason demonstrates this exposition: for, just as in verse 14 rewards are promised both to the people and to the king; so it was equal that here punishments be set forth to both. Nevertheless, he called him a Father, rather than a King, both so that he might remind him of his office/duty; and because he was treating of punishment; so that he might not appear to offend him, before he had sinned, even with a word; and so that he might bestow the honor owed to royal dignity, and so keep the Hebrews in the reverence and obedience of their Kings (Mendoza).
Your fathers: Who lived under the judges; and you shall have no advantage in that point by the change of government, nor shall your kings be able to protect you against God’s displeasure.
 Hebrew: אִם־תִּֽירְא֣וּ אֶת־יְהוָ֗ה וַעֲבַדְתֶּ֤ם אֹתוֹ֙ וּשְׁמַעְתֶּ֣ם בְּקֹל֔וֹ וְלֹ֥א תַמְר֖וּ אֶת־פִּ֣י יְהוָ֑ה וִהְיִתֶ֣ם גַּם־אַתֶּ֗ם וְגַם־הַמֶּ֙לֶךְ֙ אֲשֶׁ֣ר מָלַ֣ךְ עֲלֵיכֶ֔ם אַחַ֖ר יְהוָ֥ה אֱלֹהֵיכֶֽם׃  Hebrew: פִּי.  Hebrew: וִהְיִתֶ֣ם—אַחַ֖ר.  Numbers 27:14a: “For ye rebelled against my commandment (מְרִיתֶ֙ם פִּ֜י, ye rebelled against my mouth) in the desert of Zin, in the strife of the congregation, to sanctify me at the water before their eyes…”  Hebrew: וְאִם־לֹ֤א תִשְׁמְעוּ֙ בְּק֣וֹל יְהוָ֔ה וּמְרִיתֶ֖ם אֶת־פִּ֣י יְהוָ֑ה וְהָיְתָ֧ה יַד־יְהוָ֛ה בָּכֶ֖ם וּבַאֲבֹתֵיכֶֽם׃  Proverbs 17:3: “The fining pot is for silver, and the furnace for gold: but the Lord trieth the hearts (וּבֹחֵ֖ן לִבּ֣וֹת יְהוָֽה׃, so the Lord trieth the hearts).”  Proverbs 25:23: “The north wind driveth away rain: so doth an angry countenance (וּפָנִ֥ים נִ֜זְעָמִ֗ים) a backbiting tongue.”  Acts 8:32: “The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb (ὡς ἀμνὸς) dumb before his shearer, so not (οὕτως οὐκ) opened he his mouth…”  Amos 9:7: “Are ye not as children of the Ethiopians unto me, O children of Israel? saith the Lord. Have not I brought up Israel out of the land of Egypt? and the Philistines (וּפְלִשְׁתִּיִּים, as the Philistines) from Caphtor, and the Syrians from Kir?”  Greek: ὡς ἐν οὐρανῷ, καὶ ἐπὶ τῆς γῆς.  Acts 7:51: “Ye stiffnecked and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers did, so do ye (ὡς οἱ πατέρες ὑμῶν, καὶ ὑμεῖς).”  John 20:21: “Then said Jesus to them again, Peace be unto you: as my Father hath sent me, even so send I you (καθὼς ἀπέσταλκέ με ὁ πατήρ, κἀγὼ πέμπω ὑμᾶς).”