Verses 16, 17. - Certain rules are prescribed for the king. It is forbidden to him to multiply horses, to multiply wives, and to amass large treasures of silver and gold, and he must have a copy of the Law written out for him from that kept by the priests, that he might have it by him, and read it all the days of his life. The multiplying of horses is prohibited, because this would bring Israel into intercourse and friendly relations with Egypt, and might tend to their going back to that country from which they had been so marvelously delivered; a prohibition which could only have been given at an early stage in the history of the people, for at a later period, after they had been well established in Canaan, such a prohibition for such a reason would have been simply ridiculous. The prohibition to multiply wives and to amass large treasures has respect to the usage common from the earliest period with Oriental monarchs to have vast harems and huge accumulations of the precious metals, as much for ostentation as for either luxury or use; and as there was no small danger of the King of Israel being seduced to follow this usage, and so to have his heart turned away from the Lord, it was fitting that such a prohibition should be prospectively enacted for his guidance. Both these prohibitions were neglected by Solomon, and probably by others of the Jewish kings; but this only indicates that the law was so ancient that it had come in their time to be regarded as obsolete. The rule that the king was to write him a copy of the Law for his own constant use does not necessarily imply that he was to write this with his own hand; he might cause it to be written by some qualified scribe for him.

17:14-20 God himself was in a particular manner Israel's King; and if they set another over them, it was necessary that he should choose the person. Accordingly, when the people desired a king, they applied to Samuel, a prophet of the Lord. In all cases, God's choice, if we can but know it, should direct, determine, and overrule ours. Laws are given for the prince that should be elected. He must carefully avoid every thing that would turn him from God and religion. Riches, honours, and pleasures, are three great hinderances of godliness, (the lusts of the flesh, the lusts of the eye, and the pride of life,) especially to those in high stations; against these the king is here warned. The king must carefully study the law of God, and make that his rule; and having a copy of the Scriptures of his own writing, must read therein all the days of his life. It is not enough to have Bibles, but we must use them, use them daily, as long as we live. Christ's scholars never learn above their Bibles, but will have constant occasion for them, till they come to that world where knowledge and love will be made perfect. The king's writing and reading were as nothing, if he did not practise what he wrote and read. And those who fear God and keep his commandments, will fare the better for it even in this world.But he shall not multiply horses to himself,.... That he might not put his trust and confidence in outward things, as some are apt to trust in horses and chariots; and that he might not tyrannise over and distress his subjects by keeping a number of horses and chariots as a standing army, and chiefly for a reason that follows; he was to have no more than for his own chariot, so Jarchi, and so the Misnah (g) and Maimonides (h); the Targum of Jonathan restrains it to two:

nor cause the people to return to Egypt, to the end that he should multiply horses; which was a country that abounded with them, and therefore he was not to encourage, and much less oblige his subjects to travel thither or trade with that people for the sake of increasing his stock of horses, Isaiah 31:1.

forasmuch as the Lord hath said unto you, ye shall henceforth return no more that way; not that going into Egypt on any account whatsoever was forbidden, as for trade and merchandise in other things, or for shelter and safety, for which some good men fled thither; but for outward help and assistance against enemies, and for horses on that account, and particularly in order to dwell there, from which the Jews in the times of Jeremiah were dissuaded by him, and threatened by the Lord with destruction, in case they should, Jeremiah 42:15. When the Lord said this is not certain; it may be when they proposed to make a captain, and return unto Egypt; or he said this in his providence, this was the language of it ever since they came out of it, or however this he now said; see Deuteronomy 28:68.

(g) Sanhedrin, c. 2. sect. 4. (h) Hilchot Melachim, c. 3. sect. 3.