Deuteronomy 8:1-3

Carefully obey every command I give you today. Then you will live and grow in number, and you will enter and take the land the LORD promised your ancestors. Remember how the LORD your God has led you in the desert for these forty years, taking away your pride and testing you, because he wanted to know what was in your heart. He wanted to know if you would obey his commands. He took away your pride when he let you get hungry, and then he fed you with manna, which neither you nor your ancestors had ever seen. This was to teach you that a person does not live on bread alone, but by everything the LORD says.