Sura 18 Al-Kahf (The Cave), ayah 23

1. وَلَا تَقُولَنَّ لِشَيْءٍ إِنِّي فَاعِلٌ ذَٰلِكَ غَدًا

   And never say of anything, "Indeed, I will do that tomorrow,"

   18:23

Translation: Saheeh International