Al-An'am 6:109

Waaqsamoo billahi jahda aymanihimla-in jaat-hum ayatun layu/minunna biha qulinnama al-ayatu AAinda Allahi wamayushAAirukum annaha itha jaat layu/minoon

And they swear by Allāh their strongest oaths that if a sign came to them, they would surely believe in it. Say, "The signs are only with [i.e., from] Allāh." And what will make you perceive that even if it [i.e., a sign] came, they would not believe.

They have sworn forceful oaths by Allah that if a sign comes to them, they will surely believe in it. Say, “Signs are in Allah’s power alone.” What will make you realize that even when they (the signs) come, they will not believe?