Surah Al-Hadid (The Iron), Verse 8

وَمَا لَكُمْ لَا تُؤْمِنُوْنَ بِاللّٰهِ وَالرَّسُوْلُ یَدْعُوْكُمْ لِتُؤْمِنُوْا بِرَبِّكُمْ وَقَدْ اَخَذَ مِیْثَاقَكُمْ اِنْ كُنْتُمْ مُّؤْمِنِیْنَ ۟

Wa maa lakum laa tu'minoona billaahi war Rasoolu yad'ookum li tu'minoo bi Rabbikum wa qad akhaza meesaaqakum in kuntum mu'mineen

“What cause have ye why ye should not believe in Allah?- and the Messenger invites you to believe in your Lord, and has indeed taken your Covenant, if ye are men of Faith.”

Quran 57:8 (Yusuf Ali Translation)