Surah Al-An'aam, Verse 109
Translation — Sahih International
And they swear by Allah their strongest oaths that if a sign came to them, they would surely believe in it. Say, "The signs are only with Allah." And what will make you perceive that even if a sign came, they would not believe.
Source
Kur'an-ı Kerim, En'âm Suresi 6:109
https://kuran.diyanet.gov.tr/mushaf/kuran-meal-2/6-suresi-109-ayet