وَلَا تَقُولَنَّ لِشَيْءٍ إِنِّي فَاعِلٌ ذَٰلِكَ غَدًا ٢٣
Nor say of anything, "I shall be sure to do so and so tomorrow"-
18:24
إِلَّا أَنْ يَشَاءَ اللَّهُ ۚ وَاذْكُرْ رَبَّكَ إِذَا نَسِيتَ وَقُلْ عَسَىٰ أَنْ يَهْدِيَنِ رَبِّي لِأَقْرَبَ مِنْ هَٰذَا رَشَدًا ٢٤
Without adding, "So please Allah!" and call thy Lord to mind when thou forgettest, and say, "I hope that my Lord will guide me ever closer (even) than this to the right road."