Surah Ghafar (The Forgiver), Verse 50

قَالُوْۤا اَوَلَمْ تَكُ تَاْتِیْكُمْ رُسُلُكُمْ بِالْبَیِّنٰتِ قَالُوْا بَلٰی قَالُوْا فَادْعُوْا وَمَا دُعٰٓؤُا الْكٰفِرِیْنَ اِلَّا فِیْ ضَلٰلٍ 

Qaalooo awalam taku taateekum Rusulukum bilbaiyinaati qaaloo balaa' qaaloo fad'oo; wa maa du'aaa'ul kaafireena illaa fee dalaal

“They will say: "Did there not come to you your messengers with Clear Signs?" They will say, "Yes". They will reply, "Then pray (as ye like)! But the prayer of those without Faith is nothing but (futile wandering) in (mazes of) error!"”

Quran 40:50 (Yusuf Ali Translation)