Al-Furqan 25:57

قُلْ مَآ أَسْـَٔلُكُمْ عَلَيْهِ مِنْ أَجْرٍ إِلَّا مَن شَآءَ أَن يَتَّخِذَ إِلَىٰ رَبِّهِۦ سَبِيلًا

Qul mā asalukum ʿalayhi min ajrin illā man shāa an yattakhidha ilā rabbihi sabīlan

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