Ar-Ra'd - 13:14

لَهُ دَعْوَةُ الْحَقِّ وَالَّذِينَ يَدْعُونَ مِن دُونِهِ لاَ يَسْتَجِيبُونَ لَهُم بِشَيْءٍ إِلاَّ كَبَاسِطِ كَفَّيْهِ إِلَى الْمَاء لِيَبْلُغَ فَاهُ وَمَا هُوَ بِبَالِغِهِ وَمَا دُعَاء الْكَافِرِينَ إِلاَّ فِي ضَلاَلٍ
[13:14]
To Him is due the true prayer; and those whom they pray to besides Allah give them no answer, but (they are) like one who stretches forth his two hands towards water that it may reach his mouth, but it will not reach it; and the prayer of the unbelievers is only in error.
For Him (alone) is prayer in Truth: any others that they call upon besides Him hear them no more than if they were to stretch forth their hands for water to reach their mouths but it reaches them not: for the prayer of those without Faith is nothing but (futile) wandering (in the mind).
Unto Him is the real prayer. Those unto whom they pray beside Allah respond to them not at all, save as (is the response to) one who stretcheth forth his hands toward water (asking) that it may come unto his mouth, and it will never reach it. The prayer of disbelievers goeth (far) astray.