The Gospel of Matthew
Gaebelien: "Introduction to Matthew, Chapter 6
Christ makes now known the motive of the true righteousness, which the heirs of the kingdom are not only to possess, but also to practice. The motive is to act in the presence of the Father. tHe word Father ifs found ten times in the beginning of this chapter. The Father sees, the Father knows. Here a relationship is acknowledged and made prominent, which is unknown in the Old Testament. How the heirs of the kingdom are brought into this relationship is not taught in Matthew. The gospel of John reveals this.
In verses 1-4 we see the motive of
true righteousness in relation to man; in verses 5-15 in relation to God and in
verses 16-18 in relation to self.
In the second half of this chapter the heirs of the Kingdom are seen as in the world, subject to its cares and temptations. Our Lord tells us how to behave in the midst of the world and what are our privileges and comforts. the ;natural man lives for the earthly things; his delight is in treasures which are here below. It is to be different with the true disciple (verses 19-21). His exhortation, "Lay not up for yourselves treasures, which are on earth," read the following passages : Colossians 3:2-3; 2 Corinthians 4:18, 1 Timothy 6:9-11, :17-18; Hebrews 8:5. May we heed these words in a day when professing Christians heap together treasures in the last days (James 5:1-3).
And how great is the comfort that we have a Father, who careth! "Be not careful" -- oh, how blessed it sounds, for full and rich it comes to the heart of the believer! And it is the Son of God who exhorts us to trust the Father, who gives us the assurance we seek first the Kingdom of God and His righteousness, that all these things shall be added unto us.
 Gaebelein, Arno C. (c. 1970). "The Holy Scriptures Analyzed and Annotated: Matthew" - Moody Press, Loizeaux Bothers