Quran 7:183 from Surah Al-A'raaf on Divine Marvels.
وَأُمۡلِي لَهُمۡۚ إِنَّ كَيۡدِي مَتِينٌ
English translation: And I will give respite to them Indeed My plan (is) firm
Transliteration: wa-um'li lahum inna kaydi matinun