Qur'an 17:9

إِنَّ هَـٰذَا ٱلْقُرْءَانَ يَهْدِى لِلَّتِى هِىَ أَقْوَمُ وَيُبَشِّرُ ٱلْمُؤْمِنِينَ ٱلَّذِينَ يَعْمَلُونَ ٱلصَّـٰلِحَـٰتِ أَنَّ لَهُمْ أَجْرًا كَبِيرًا

Lo! this Qur'an guideth unto that which is straightest, and giveth tidings unto the believers who do good works that theirs will be a great reward.