The next morning after Jesus has fed the crowds of people they go looking for Him again. It is very clear that they have no desire for Jesus, God, eternal life, etc.; all they want is free food.
Jesus tells them to labor for eternal things, not temporal
Jesus refuses to feed them because their greatest need is the eternal life that is found in Him. He offers Himself to them instead of food, but they are only interested in free food.
Jesus is the manna from heaven
Jesus says that manna in the Old Testament was a picture of Him. Just as manna sustained the children of Israel, so He sustains us and gives us life. We need Jesus, not earthly things.
All the Father gives will come to Jesus
Jesus knows that only the Father can give people a new life in Him. Because of this, He is not interested in gathering huge crowds by feeding them constantly. He is only interested in people having a new life. He rests in God’s provision of salvation, not His ability to draw a crowd. He is not concerned with how many people follow Him; He is only concerned with glorifying God.
The flesh profits nothing, only the Spirit gives life
Using fleshly means to attract people does not help them find eternal life. Only the Spirit of God can give life. As such, we, like Jesus, should not use fleshly means to attract people. We should instead seek to glorify God and trust that the Spirit will draw men to Him.
We must crucify our flesh and seek Christ. We must seek God’s glory, not crowds.