Deuteronomy 33:15

And for the chief things of the ancient mountains, and for the precious things of the lasting hills,

The blessing speaks of the finest and most precious products and resources of the ancient mountains and enduring hills as part of the promised land, showing the rich abundance and beauty given to Israel. Its mountains were clothed with cedars, and its hills were gray with olives and fragrant with vines, fruitful vines displaying that abundance. The vision of Canaan is thus one of natural richness poured out from mountain and hill alike.

The lasting hills picture being fixed and immovable. They therefore call for taking a firm, wise, and cautious stand on what God has plainly spoken, calm as a summer evening yet unyielding, and for making no concession on any such point. To concede is to sell the whole cause of God into the hands of the enemy, and that cause is never to be traded away but to be taken hold of decidedly.