The horse was not anciently used in the East for purposes of agriculture or traveling, but ordinarily for war only. He appears constantly in Scripture as the symbol and embodiment of fleshly strength and the might of the creature (compare Psalms 20:7; Psalms 33:16-17; Psalms 147:10; Job 39:19 ff), and is sometimes significantly spoken of simply as “the strong one” (compare Jeremiah 8:16). The spirit of the prohibition therefore is that the king of Israel must not, like other earthly potentates, put his trust in costly and formidable preparations for war (compare Hosea 1:7).
Egypt was the principal source from where the nations of western Asia drew their supplies of this animal (compare Exodus 14:5 ff; 1 Kings 10:28-29; 2 Kings 7:6); but contact, traffic, or alliance which would “cause the people to return to Egypt” would be to reverse that great and beneficent wonderwork of God which inaugurated the Mosaic covenant, the deliverance from the bondage of Egypt; and to bring about of set purpose that which God threatened Deuteronomy 28:68 as the most severe punishment for Israel’s sin.