Surah Yusuf, ayah 104

12:104

وَمَا تَسۡـَٔلُهُمۡ عَلَيۡهِ مِنۡ أَجۡرٍۚ إِنۡ هُوَ إِلَّا ذِكۡرٞ لِّلۡعَٰلَمِينَ ١٠٤

Wamā tas'aluhum 'alayhi min ajrin in huwa illā dhikrul lil-'ālamīn

And you do not ask of them for it any payment. It is not except a reminder to the worlds.