"The whole commandment which I am commanding you today, you shall keep and do, so that you may live and multiply, and enter and possess the land which Jehovah swore to your fathers" (8:1). Whereas the children of Israel were to keep the whole law, we need to keep the whole Christ so that the church may have both longevity and multiplication.
"You shall remember all the way that Jehovah your God has led you these forty years in the wilderness in order to humble you and test you that He might know what was in your heart, whether you would keep His commandments or not. And He humbled you and let you go hungry and fed you the manna, which you had never known nor had your fathers ever known, so that He might make you know that man lives not by bread alone, but that man lives by everything proceeding from Jehovah's mouth" (vv. 2-3). Here Moses charged the people to remember how God humbled them, let them go hungry, and then fed them with manna so that they might learn that man does not live by bread alone but by whatever proceeds out of Jehovah's mouth.
In Matthew 4:4 the Lord Jesus quoted Deuteronomy 8:3, saying, "Man shall not live on bread alone, but on every word that proceeds out through the mouth of God." When He quoted this verse, He surely knew that "every word" refers to the law, the commandments, the ordinances, the statutes, and the judgments. All these are the words that have proceeded out of God's mouth as God's breathing, and they all refer to Christ. Therefore, to live by every word that proceeds out through the mouth of God is to live by Christ.
In Deuteronomy 8:4 and 5 Moses went on to say, "Your clothing did not wear out from upon you, nor did your foot swell these forty years. Know then in your heart that as a man disciplines his son, so Jehovah your God was disciplining you." During the years in the wilderness, Jehovah had dealt with the people strictly and severely. That was His loving discipline. Because He loved the children of Israel, He disciplined them.