Ether 3:26

for the Lord had said unto him in times before, that if he would believe in him, that he could shew unto him all things—it should be shewn unto him; therefore the Lord could not withhold any thing from him: for he knew that the Lord could shew him all things.

The Lord had told him before: “If you believe in me, I can show you all things.” So the Lord couldn’t hide anything from him. The brother of Jared knew the Lord could show him everything.

The Lord had told him before: if he would believe, the Lord could show him everything. And so the Lord couldn’t hold anything back from him, because this man knew the Lord could show him all things.