Surah Yasin, ayah 21

ٱتَّبِعُواْ مَن لَّا يَسۡـَٔلُكُمۡ أَجۡرٗا وَهُم مُّهۡتَدُونَ ٢١

Ittabi'ū mal lā yas'alukum ajran wahum muhtadūn

Follow those who do not ask of you [any] payment, and they are [rightly] guided.