Surah Al-An'am (The Cattle), Verse 35

وَاِنْ كَانَ كَبُرَ عَلَیْكَ اِعْرَاضُهُمْ فَاِنِ اسْتَطَعْتَ اَنْ تَبْتَغِیَ نَفَقًا فِی الْاَرْضِ اَوْ سُلَّمًا فِی السَّمَآءِ فَتَاْتِیَهُمْ بِاٰیَةٍ وَلَوْ شَآءَ اللّٰهُ لَجَمَعَهُمْ عَلَی الْهُدٰی فَلَا تَكُوْنَنَّ مِنَ الْجٰهِلِیْنَ ۟

Wa in kaana kabura 'alaika i'raaduhum fa inistata'ta an tabtaghiya nafaqan fil ardi aw sullaman fis samaaa'i fata' tiyahum bi Aayah; wa law shaaa'al laahu lajama'ahum 'alal hudaa; falaa takoonanna minal jaahileen

“If their spurning is hard on thy mind, yet if thou wert able to seek a tunnel in the ground or a ladder to the skies and bring them a sign,- (what good?). If it were Allah's will, He could gather them together unto true guidance: so be not thou amongst those who are swayed by ignorance (and impatience)!”

Quran 6:35 (Yusuf Ali Translation)