Is the worshipping of a person who does not perform five daily prayers not accepted?
What is meant by that expression in the hadiths is that the
worshipping will not be expected in the perfect manner.
It will be wrong to say that the other worshipping of a
person who does not perform five daily prayers is not accepted because Allah
does not let any good deed disappear. However, since prayer (salah) is the
essence of all kinds of worshipping and since a person who does not perform
prayers is regarded to have committed sins, the reward he gets from other kinds
of worshipping will decrease. That is, he cannot obtain the perfect rewards but
his deeds are valid.