Notice that Jesus has established a higher calling than obeying the Commandments of God. Thus, Jesus is showing that there is something greater than the Commandments here. What is greater than the Commandments of God? Only God, Himself.
So, in order to be perfect, Jesus says, "you must not only keep the Commandments, but also divest yourself of all worldly possessions and then, one more thing, focus completely on me."