Al-Furqan 25:57

Qul ma as-alukum AAalayhi min ajrinilla man shaa an yattakhitha ilarabbihi sabeela

Say, "I do not ask of you for it any payment - only that whoever wills might take to his Lord a way."

Say, “I do not demand from you any return, except that one should adopt the (proper) way to his Lord, if he so wills.