John Calvin on Numbers 13:18-21

18. And see the land what it is. The counsel of Moses had this object, that the people might be made aware how rich and fertile the land was; for a barren country does not support a large population; and the healthfulness of a locality is inferred from the rigor of its inhabitants, tie, therefore, chiefly insists on the goodness of the land and its abundant production of fruits. Still, perhaps, God would intentionally have the Israelites forewarned, that they would have to do with strong and powerful enemies; lest they might be alarmed and discouraged at suddenly beholding them. But the main point was, that the pleasantness and fertility of the land might allure them to take possession of it.