Deuteronomy 26
v1-11: By giving "to God the first and best that we have," we show that we "believe him to be the first and best of Beings," and the "giver of all the good things" we need to "support and strengthen" our lives. It is right that we glorify Him before satisfying our "own appetites and desires."
v12-15: It should not surprise us that "God, who gives us everything we have according to his providence, should direct us in his Law as to how we should use it."
v16-19: Out of "duty and gratitude" we are to obey God. He has given us His laws and commands and we are not to "argue with them but put them into practice." God has chosen us and saved us to be His holy people and to do good works.
Deuteronomy 27
v1-10: When the Israelites entered the Promised Land, the words of the Law were to be written on plastered stone with an altar set up close to it. "This shows that we can look with confidence on the Law only because of the great sacrifice by which atonement is made for sin. Without that sacrifice, the Law only makes us aware that we have broken it."
v11-13: The tribe of Levi is included with the rest of the tribes, because the blessings and curse which they preach to others, apply to them too. This is important for those who preach God's Word to others to remember.
v14-26: Every time the people of Israel said "Amen" to the curse for breaking the Law, "they were in effect saying not only, "It is certain it will be so," but also, "it is right it should be so." They were acknowledging the justice of the wrath of God against human ungodliness and unrighteousness. The comforts of the gospel shine more brightly against the backdrop of the terrors of the Law, so we need to hear both preached.