 In that passage, that verse is couched in this kind of context. They're talking about food, clothing, and shelter. And Jesus was saying, don't worry about these things. Don't focus your attention upon these things. Don't seek after this. But you seek, set your priority on things above. He said, seek ye first the kingdom of God. That's the rule of Christ in your heart. And his righteousness, that is the character of Christ in your life.