18:23
وَلَا تَقُولَنَّ لِشَا۟ىْءٍ إِنِّى فَاعِلٌۭ ذَٰلِكَ غَدًا ٢٣
Saheeh International
And never say of anything, "Indeed, I will do that tomorrow,"
Tafsir of "Ibn Kathir" (English)
Saying "If Allah wills" when determining to do Something in the Future Allah says:وَلَا تَقُولَنَّ لِشَيْءٍ إِنِّي فَاعِلٌ ذَلِكَ غَدًا