The foundation for this is Jesus himself. This is his call, his way, his will. Jesus “took off” his divinity in order to come to us. He left the glory of heaven to spend time with us on earth. He became poor that we might become rich. We are invited to have the same attitude that is found in Jesus, who though he was in the form of God did not deem equality with God as something to be exploited.
The focus is not simply on Levi's becoming poor. He also became rich as Jesus filled his heart with desire. Jesus calls us too, to an ever-deepening conversion, responding to his invitation. He will not leave us in our poverty, but invites us to the feast in the kingdom too.
 Phil 2:5