Surah Saba' (The Sheba), Verse 21

وَمَا كَانَ لَهٗ عَلَیْهِمْ مِّنْ سُلْطٰنٍ اِلَّا لِنَعْلَمَ مَنْ یُّؤْمِنُ بِالْاٰخِرَةِ مِمَّنْ هُوَ مِنْهَا فِیْ شَكٍّ وَرَبُّكَ عَلٰی كُلِّ شَیْءٍ حَفِیْظٌ 

Wa maa kaana lahoo 'alaihim min sultaanin illaa lina'lama mai yu minu bil Aakhirati mimman huwa minhaa fee shakk; wa Rabbuka 'alaa kulli shai'in Hafeez

“But he had no authority over them,- except that We might test the man who believes in the Hereafter from him who is in doubt concerning it: and thy Lord doth watch over all things.”

Quran 34:21 (Yusuf Ali Translation)