(Al-Kahf) 18 : 24
إِلَّا أَنْ يَشَاءَ اللَّهُ ۚ وَاذْكُرْ رَبَّكَ إِذَا نَسِيتَ وَقُلْ عَسَىٰ أَنْ يَهْدِيَنِ رَبِّي لِأَقْرَبَ مِنْ هَٰذَا رَشَدًا
Except: "If Lord Allah wishes". And remember your Lord when you forget and say: "Perhaps my Lord will guide me to what is nearer than this to the Upright way".
Lord’s Book was not codified during the time of Messenger. But today, Adhikr which is the Lord’s Permission is codified as a Book. So whoever holdfasts It, he did holdfast Lord and is guided into the Straightpath as explained in verses 3: 101-102. See explanation 3: 79 and 5: 48.