So they rose early in the morning and went out into the wilderness of Tekoa; and as they went out, Jehoshaphat stood and said, Listen to me, O Judah and you inhabitants of Jerusalem: Trust in Jehovah your God, and you shall be established; believe His prophets, and you shall prosper.

because they did not believe in God, and did not trust in His salvation;

Then they despised the pleasant land; they did not believe His Word,

And the head of Ephraim is Samaria, and the head of Samaria is Remaliah's son. If you will not believe, surely you shall not be established.

Beware, brethren, that there not be in any of you an evil heart of unbelief in withdrawing from the living God;

And to whom did He swear that they would not enter His rest, but to those who did not obey?

So we see that they could not enter in because of unbelief.

But I want to remind you, though you once knew this, that the Lord, having saved the people out of the land of Egypt, afterward destroyed those who did not believe.