One thing have I desired of the LORD, that will I seek after; that I may dwell in the house of the LORD all the days of my life, to behold the beauty of the LORD, and to inquire in his temple. (Psalm 27:4)
Absolutely beautiful. The single mindedness of David's desire - that he may dwell in the house of the Lord, that he might see His glory displayed. Christ said to "seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you."(Matthew 6:33) We are to seek the Father's will, to desire God above all. We are to love Him first and foremost, in the midst of joyful times, in the midst of trying and sorrowful times He is to come first.
For in the time of trouble he shall hide me in his pavilion: in the secret of his tabernacle shall he hide me; he shall set me up upon a rock. And now shall mine head be lifted up above mine enemies round about me: therefore will I offer in his tabernacle sacrifices of joy; I will sing, yea, I will sing praises unto the LORD. (Psalm 27:5-6)
Paul espoused the same idea, to desire God above all...Including our own lives, in fact he encourages us to view our troubles especially as a token of our salvation.
Only let your conversation be as it becometh the gospel of Christ: that whether I come and see you, or else be absent, I may hear of your affairs, that ye stand fast in one spirit, with one mind striving together for the faith of the gospel; And in nothing terrified by your adversaries: which is to them an evident token of perdition, but to you of salvation, and that of God. (Philippians 1:27-28)
When my father and my mother forsake me, then the LORD will take me up. (Psalm 27:10)
Christ Himself told us that if we follow Him, if we seek the Father's will, if we truly desire God above all else we will be hated because He was hated (Matthew 10). He said that brother would deliver up brother, father would deliver up son, the betrayal would be great (Matthew 10:21, Matthew 24:10, Luke 12:53). Christ said that whoever loves his father, mother, or child more than him was not worthy of Him (Matthew 10:37, Luke 14:26, 33), He knew how fickle the human heart was, how deceitful it can be, how disloyal. This is why we must love Him above all, seek Him above all. For "the LORD will take me up," (Psalm 27:10) even when all else fails His faithfulness will stand. To love anything else more is pure foolishness, it would be like building a house on sand. When the other love stumbles, removes itself from our life, or we lose interest in it the house will collapse, having nothing to stand on.
A double minded man is unstable in all his ways. (James 1:8)
And this is why the single mindedness of verse four is so beautiful, we see in David an example of what the New Testament commands of us - to seek Him first.