This “word of the Lord” is found in Joshua 6:26, after Jericho was completely obliterated. Joshua, through the Spirit, on behalf of the Lord, pronounced the solemn oath that is now executed in the days of Ahab, who dared to defy the LORD’s oath and rebuild Jericho as a fortress.
34 In his days Hiel of Bethel built Jericho. He laid its foundation at the cost of Abiram his firstborn, and set up its gates at the cost of his youngest son Segub, according to the word of the LORD, which he spoke by Joshua the son of Nun.