In the Book of Deuteronomy, we hear Moses saying to the people of Isreal before entering the promised land:
“2 Now you shall remember the whole way the Lord your God led you in the desert, to deal harshly with you and test you, to know what was in your heart, whether you would keep His commandments or not.Deuteronomy 8:2-6
3 So He dealt harshly with you and weakened you with hunger, and fed you with manna, which your fathers did not know, that He might make you know that man shall not live by bread alone, but by every word proceeding from the mouth of God man shall live.
4 Your garments did not wear out on you, nor did your feet become callused these forty years.
5 You should know in your heart that as a man chastens his son, so the Lord your God chastens you.
6 Therefore, you shall keep the commandments of the Lord your God to walk in His ways and to fear Him.”
Then long after, Jesus Christ used the same verses in Deuteronomy 3 to respond to the Devil:
“3 Now when the tempter came to Him, he said, “If You are the Son of God, command that these stones become bread.” 4 But He answered and said, “It is written, ‘Man shall not live by bread alone, but by every word that proceeds from the mouth of God.’ ”.”Matthew 4:3-4
The Lord dealt harshly with Israel in the desert as a test, for testing under pressure has a way of revealing what is in the heart. The test in each case reveals obedience or disobedience to His commandments. This revelation was not for the Lord’s acquisition of knowledge, for He knows all things before they occur. Instead, it would let each of them know the condition of his own heart. All chastening is for the benefit that we might partake of the Lord’s holiness.
The Lord allowed them to go hungry in the desert and fed them with simple food: manna, of which they grew sick. Nevertheless, the Lord was teaching them the road of virtue, namely, that man’s primary food is the word of God and obedience to that word. But they failed to learn this lesson, and many died in the desert.
Athanasius Academy of Orthodox Theology, Elk Grove, California. The Orthodox Study Bible. Nashville: Thomas Nelson, 2008.