And he lifted up his eyes on his disciples, and said, Blessed be ye poor: for yours is the kingdom of God.Matthew 5:3:
Blessed are the poor in spirit: for theirs is the kingdom of heaven.Matthew's version raises a question: "What does it mean to be poor 'in spirit'?" The answer's simple if you look at what Jesus says elsewhere about wealth and poverty. From Matthew 19:21:
Jesus said unto him, If thou wilt be perfect, go and sell that thou hast, and give to the poor, and thou shalt have treasure in heaven: and come and follow me.Luke cuts to the chase: The blessed are poor. Matthew tells how to become blessed if you're rich.
Matthew and Luke know that's hard for rich people to hear. Both of their stories about the rich young man, and Mark's as well, have Jesus's followers asking how any rich person could be saved. Jesus answers that with God, all things are possible. Greedy people say this means God will perform special miracles for them to save them. But Jesus is only noting that some rich people, upon thinking about God and people and justice and happiness, will understand that we find the way to heaven by sharing freely.
Bonus link: Eye of a needle in Judaism, Christianity, and Islam.