Commentary on the Bible, by Adam Clarke, , at sacred-texts.com
All sacrifices to be without blemish, Deu 17:1. Of persons consisted of idolatry and their punishment, Deu 17:2-7. Difficult matters in judgment to be laid before the priests and judges, and to be determined by them; and all to submit to their decision, Deu 17:8-13. The king that may be chosen to be one of their brethren; no stranger to be appointed to that office, Deu 17:14, Deu 17:15. He shall not multiply horses to himself, nor cause the people to return unto Egypt, Deu 17:16. Nor multiply wives, money, etc., Deu 17:17. He shall write a copy of the law for his own use, and read and study it all his days, that his heart be not lifted up above his brethren, Deu 17:18-20.
Wherein is blemish - God must not have that offered to him which thou wouldst not use thyself. This not only refers to the perfect sacrifice offered by Christ Jesus, but to that sincerity and uprightness of heart which God requires in all those who approach him in the way of worship.
If it be told thee - In a private way by any confidential person. And thou hast heard of it; so that it appears to be notorious, very likely to be true, and publicly scandalous. And hast inquired diligently - sought to find out the truth of the report by the most careful examination of persons reporting, circumstances of the case, etc. And, behold, it be true - the report is not founded on vague rumor, hearsay, or malice. And the thing certain - substantiated by the fullest evidence. Then shalt thou bring forth that man, Deu 17:5. As the charge of idolatry was the most solemn and awful that could be brought against an Israelite, because it affected his life, therefore God required that the charge should be substantiated by the most unequivocal facts, and the most competent witnesses. Hence all the precautions mentioned in the fourth verse must be carefully used, in order to arrive at so affecting and so awful a truth.
Two witnesses - One might be deceived, or be prejudiced or malicious; therefore God required two substantial witnesses for the support of the charge.
If there arise a matter too hard for thee - These directions are given to the common magistrates, who might not be able to judge of or apply the law in all cases that might be brought before them. The priests and Levites, who were lawyers by birth and continual practice, were reasonably considered as the best qualified to decide on difficult points.
The man that will do presumptuously - The man who refused to abide by this final determination forfeited his life, as being then in a state of rebellion against the highest authority, and consequently the public could have no pledge for his conduct.
One from among thy brethren shalt thou set king over thee - It was on the ground of this command that the Jews proposed that insidious question to our Lord, Is it lawful to give tribute to Caesar, Or No? Mat 22:17; for they were then under the authority of a foreign power. Had Christ said Yes, then they would have condemned him by this law; had he said No, then they would have accused him to Caesar. See this subject discussed in great detail in the notes, Mat 22:16 (note), etc.
He shall not multiply horses - As horses appear to have been generally furnished by Egypt, God prohibits these,
1. Lest there should be such commerce with Egypt as might lead to idolatry.
2. Lest the people might depend on a well-appointed cavalry as a means of security, and so cease from trusting in the strength and protection of God. And,
3. That they might not be tempted to extend their dominion by means of cavalry, and so get scattered among the surrounding idolatrous nations, and thus cease, in process of time, to be that distinct and separate people which God intended they should be, and without which the prophecies relative to the Messiah could not be known to have their due and full accomplishment.
Neither shall he multiply wives - For this would necessarily lead to foreign alliances, and be the means of introducing the manners and customs of other nations, and their idolatry also. Solomon sinned against this precept, and brought ruin on himself and on the land by it; see Kg1 11:4.
He shall write him a copy of this law - משנה התורה הזאת mishneh hattorah hazzoth, an iteration or duplicate of this law; translated by the Septuagint, το δευτερονομιον τουτο this deuteronomy. From this version both the Vulgate Latin and all the modern versions have taken the name of this book; and from the original word the Jews call it Mishneh. See the preface to this book.
Out of that which is before the priests the Levites - It is likely this means, that the copy which the king was to write out was to be taken from the autograph kept in the tabernacle before the Lord, from which, as a standard, every copy was taken and with which doubtless every copy was compared; and it is probable that the priests and Levites had the revising of every copy that was taken off, in order to prevent errors from creeping into the sacred text.
And it shall be with him, etc. - It was the surest way to bring the king to an acquaintance with the Divine law to oblige him to write out a fair copy of it with his own hand, in which he was to read daily. This was essentially necessary, as these laws of God were all permanent, and no Israelitish king could make any new law, the kings of this people being ever considered as only the vice-gerents of Jehovah.
He, and his children, in the midst of Israel - From this verse it has been inferred that the crown of Israel was designed to be hereditary, and this is very probable; for long experience has proved to almost all the nations of the world that hereditary succession in the regal government is, on the whole, the safest, and best calculated to secure the public tranquillity.