Deuteronomy 17:16
14 When you come to the land the Lord your God is giving you and take it over and live in it and then say, “I will select a king like all the nations surrounding me,” 15 you must select without fail a king whom the Lord your God chooses. From among your fellow citizens you must appoint a king—you may not designate a foreigner who is not one of your fellow Israelites. 16 Moreover, he must not accumulate horses for himself or allow the people to return to Egypt to do so, for the Lord has said you must never again return that way. 17 Furthermore, he must not marry many wives lest his affections turn aside, and he must not accumulate much silver and gold.
Isaiah 2:7
6 Indeed, O Lord, you have abandoned your people, the descendants of Jacob. For diviners from the east are everywhere; they consult omen readers like the Philistines do. Plenty of foreigners are around. 7 Their land is full of gold and silver; there is no end to their wealth. Their land is full of horses; there is no end to their chariots. 8 Their land is full of worthless idols; they worship the product of their own hands, what their own fingers have fashioned.
Notes and References
"... Deuteronomy focuses much less on what the king must do than on what he must not do (17:16-17) ... These three restrictions “quite explicitly cut against the accepted pattern of kingship throughout the ancient Near East.” As Bible scholar Christopher Wright explains, “military power (the point of having great numbers of horses), the prestige of a large harem (frequently related to international marriage alliances), and great wealth (large amounts of silver and gold)—these were the defining marks of kings worthy of the title... But Deuteronomy starkly declares: ‘Not so in Israel.’” Why are weapons, wives, and wealth considered so dangerous? Cavalry and chariots signal a king’s self-glorification. When David’s sons Absalom and Adonijah seek to become king, each “provides himself with a chariot, horses, and fifty outrunners” (2 Samuel 15:1; 1 Kings 1:5). Moreover, massive military power can delude kings into thinking that they are “self-sufficient and not dependent on God.” Indeed, for the prophets, a massive chariot force is a sign of infidelity to God: Isaiah condemns the people because “their land is full of horses, and there is no limit to their chariots” (Isaiah 2:7) and Micah foresees a day when God “will destroy the horses in your midst and wreck your chariots” (Micah 5:10). Faithful followers of God, in contrast, declare: “They call on chariots, they call on horses, but we call on the name of the Lord our God” (Psalm 20:8) ..."
Held, Shai Give the People (Only Some of) What They Want: Deuteronomy and the King (pp. 1-10) Center for Jewish Leadership and Ideas, 2014