But as for you, your carcasses, they shall fall in this wilderness.

Wesley's Notes

14:32 Your carcases - See with what contempt they are spoken of, now they had by their sin made themselves vile! The mighty men of valour were but carcases, now the Spirit of the Lord was departed from them! It was very probably upon this occasion, that Moses wrote the ninetieth psalm.

Matthew Henry's Concise Commentary

14:20-35 The Lord granted the prayer of Moses so far as not at once to destroy the congregation. But disbelief of the promise forbids the benefit. Those who despise the pleasant land shall be shut out of it. The promise of God should be fulfilled to their children. They wished to die in the wilderness; God made their sin their ruin, took them at their word, and their carcases fell in the wilderness. They were made to groan under the burden of their own sin, which was too heavy for them to bear. Ye shall know my breach of promise, both the causes of it, that it is procured by your sin, for God never leaves any till they first leave him; and the consequences of it, that will produce your ruin. But your little ones, now under twenty years old, which ye, in your unbelief, said should be a prey, them will I bring in. God will let them know that he can put a difference between the guilty and the innocent, and cut them off without touching their children. Thus God would not utterly take away his loving kindness.