وَإِذْ تَأَذَّنَ رَبُّكُمْ لَئِن شَكَرْتُمْ لَأَزِيدَنَّكُمْ ۖ وَلَئِن كَفَرْتُمْ إِنَّ عَذَابِى لَشَدِيدٌ 14:7
Wa-ith taaththana rabbukumla-in shakartum laazeedannakum wala-in kafartum inna AAathabeelashadeed
And when your Lord proclaimed: If ye give thanks, I will give you more; but if ye are thankless, lo! My punishment is dire.