Repenting of trust in Assyria makes some intuitive sense: trusting your enemy to be your production is madness. But what then about refusing to trust in “horses”? And so Sibbes takes up the clause, 

‘We will not ride upon horses.’

He begins with the manner in which horses are described in Scripture. 

What kind of creature a horse is, it is worth the seeing. What a description God gives of him, that we may see what reason the Spirit of God hath to instance in the horse. 

First the positive:

Saith God to Job, ‘Hast thou given the horse strength? hast thou clothed his neck with thunder? canst thou make him afraid as a grasshopper? the glory of his nostrils is terrible. He paweth in the valley, and rejoiceth in his strength: he goeth on to meet the armed men. He mocketh at fear, and is not affrighted; neither turneth he back from the sword. The quiver rattleth against him, the glittering spear and the shield. He swalloweth the ground with fierceness and rage: neither believeth he that it is the sound of the trumpet. He saith among the trumpets, Ha, ha; and he smelleth the battle afar off, the thunder of the captains, and the shouting,’ Job 39:19–21. A notable and excellent description of this warlike creature. 

Then the negative:

And yet for all this excellency, so described by the Spirit of God, in another place the psalmist saith, ‘A horse is a vain thing for safety, neither shall he deliver any by his great strength,’ Ps. 33:17. ‘Some trust in chariots, and some in horses; but we will remember the name of the Lord our God,’ Ps. 20:7. So in another place, ‘The horse is prepared against the day of battle, but victory is of the Lord,’ Prov. 21:31.

Why would the Scripture contain a disparagement of horses?

How oft have you in the Psalms that proud warlike creature disparaged, because naturally men are more bewitched with that than with any other creature. If they have store of horses, then they think they are strong. 

Therefore God forbids the king ‘to multiply horses to himself, nor cause the people to return to Egypt, to the end he should multiply horses,’ &c., Deut. 17:16, because God is the strength of his church, when there is no multitude of horses. You see it is a bewitching creature, and yet a vain help. 

Horses are useful for what they are fit to do. But due to their magnificence, we will be tempted to trust them for what they cannot do.

At this point, Sibbes makes an interesting aside. He applies the argument which he has made about horses to good works generally. We can so easily overvalue or misvalue:

A place like this we have, Isa. 2:7, complaining there of the naughty people which were among the Jews, at that time as bad as the Israelites. Saith he, ‘Their land also is full of silver and gold; neither is there any end of their treasures; their land is also full of horses, neither is there any end of their chariots.’ What, is there a fault in that? No. Luther saith, ‘Good works are good, but the confidence in them is damnable.’ 

And this over-valuation of the creation, putting an existential trust in the creature is idolatry:

So gold and silver, horses and chariots, are good creatures of God. But this was their sin, confidence in these things. ‘There is no end of their treasures.’ If they had treasure enough, they should do well enough. ‘Their land also was full of horses.’ Was this a fault? No; but their confidence in them. They thought they were a wise people to have such furniture and provision of munition for war. But God was their king, and the chief governor of his people; and for them to heap up these things, to trust over-much in them, it was a matter of complaint. ‘Their land also is full of idols.’

Thus you see there is no confidence to be put neither in the one nor the other, neither in the association of foreign friends, who will prove deceitful, ‘reeds of Egypt,’ that not only deceive, but the splinters thereof fly about, and may run up into the hand. Such are idolaters and false friends, deceitful and hurtful. Nor in home. There is no trust in horses, munition, or such like. What doth this imply? 

Horses are and useful for war; and yet we should not put our trust in them. Whath conclusion can we draw? First, we can conclude that warfare is not per se evil. This would be derived from the concept that God praises horses for their strength in war. He bolsters this with additional references:

That to war and have provision in that kind is unlawful and unnecessary, because he finds fault here with horses and the like? No; take heed of that; for John Baptist, if the soldier’s profession had been unlawful, he would have bid them cast away their weapons; but he bids them ‘do violence to no man, neither accuse any falsely,’ &c., Luke 3:14. And God would never style himself ‘the Lord of hosts, and a man of war,’ Isa. 42:13, and ‘he that teacheth our hands to war, and our fingers to fight,’ Ps. 18:34, unless it were good in the season. Therefore war is lawful, seeing in the way to heaven we live in the midst of enemies. Therefore it is but an anabaptistical fancy to judge war to be unlawful. 

But the question about warfare is not the point of the passage. The passage condemns the way in which we put hope in the creature:

No, no; it is clean another thing which the Holy Ghost aims at: to beat back carnal confidence. For it is an equal fault to multiply help and to neglect them. Either of both are fatal many times: to multiply horses, trusting in them, or to spoil horses and other helps vainly, so to weaken a kingdom. 

Thus, we do not neglect the use of means; but we must also not trust in the means. We make use of the means given by God and then put our trust in God:

Therefore there is a middle way for all outward things, a fit care to serve God’s providence, and when we have done, trust in God without tempting of him; for to neglect these helps is to tempt him, and to trust in them, when we have them, is to commit idolatry with them. Beware of both these extremes, for God will have his providence served in the use of lawful means. When there is this great care in a Christian commonwealth, there is a promise of good success, because God is with us. Otherwise, what is all, if he be our enemy?