both the belief in God's religion +
and he also having prosperity in the life of the World .
This poetry is known in Arabic, which I heard Abu Abd-Allah reading it many times.
That is because some believers are poor, others have disease problems, and others may have much difficulties in the life.
Yet other believers have a good prosperous life in the World in addition to their belief in God's religion i.e. the exclusive devotion to God alone .. and in this case it is the true success and happiness to which man should be grateful to God.
The completion of this poetry:
What's the benefit from mere success in the life of the World,
without having the belief in God's religion!?
It will be then the extreme loss and failure: to have the material prosperity without the belief in God's religion: the exclusive devotion to God alone.
Because the Next Life is more valuable than this short temporary life of the World.