Surah Al-Kahf Ayahs #26 Translated in English

They [i.e., people] will say there were three, the fourth of them being their dog; and they will say there were five, the sixth of them being their dog - guessing at the unseen; and they will say there were seven, and the eighth of them was their dog. Say, [O Muḥammad], "My Lord is most knowing of their number. None knows them except a few. So do not argue about them except with an obvious argument and do not inquire about them among [the speculators] from anyone."

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

Except [when adding], "If Allāh wills." And remember your Lord when you forget [it] and say, "Perhaps my Lord will guide me to what is nearer than this to right conduct."

And they remained in their cave for three hundred years and exceeded by nine.

Say, "Allāh is most knowing of how long they remained. He has [knowledge of] the unseen [aspects] of the heavens and the earth. How Seeing is He and how Hearing! They have not besides Him any protector, and He shares not His legislation with anyone."