The passage in Isaiah 13:17 was very confusing to me. It says “Behold, I will stir up the Medes against them, which shall not regard silver; and as for gold, they shall not delight in it.”
Bible Hub gives this explanation: “Which shall not regard silver.—The Medes are represented as a people too fierce to care for the gold and silver in which Babylon exulted. They would take no ransom to stay their work of vengeance. So Xenophon, in his Cyropædia (5:3), represents Cyrus as acknowledging their unbought, unpaid service.”
Which shall not regard silver “Who shall hold silver of no account” – That is, who shall not be induced, by large offers of gold and silver for ransom, to spare the lives of those whom they have subdued in battle; their rage and cruelty will get the better of all such motives. We have many examples in the Iliad and in the Aeneid of addresses of the vanquished to the pity and avarice of the vanquishers, to induce them to spare their lives.
The explanation I like best is that they wish so much destruction upon them that they care not for gold or silver.