The revelation in the Qur'an is that in this world the rich must give to the poor to guarantee a place in heaven with the angels and Allah. In practice, therefore, almsgiving is an insurance policy to be entitled to heaven. The gathering of alms also exemplifies to Muslims that they are an umma, a community.
Such generosity is based on two teachings. First, as we have seen, all goods are gifts of God and God has told us to share them. Secondly, these gifts are blessings and rewards from God and will be taken away if not used rightly. For Muslims, giving to the poor is not optional; it is the duty of bowing with one's goods. There are no exceptions — all are expected to give annually. In practice, this means that a Muslim who makes $40,000 gives about $1,000 off the net income.
Giving to the poor is not a matter of mercy or charity on the devotee's behalf. It is a matter of justice.
For the Muslim, God does not plan for his creatures to be poor. A Muslim feels blessed for being alive and understands that he is created by God and so surrenders his life to God. As part of his surrender, islam, the Muslim provides for the poor and thus receives God's mercy and goodness through economic prosperity.
— Mary Margaret Funk, Islam Is