(60) باب بَيَانِ الْوَسْوَسَةِ فِي الإِيمَانِ وَمَا يَقُولُهُ مَنْ وَجَدَهَا
It is narrated on the authority of Abu Huraira that the Messenger of Allah (ﷺ) said:
Men will continue to question one another till this is propounded: Allah created all things but who created Allah? He who found himself confronted with such a situation should say: I affirm my faith in Allah.
Reference: Sahih Muslim 134 a
In-book reference: Book 1, Hadith 250
USC-MSA web (English) reference(deprecated numbering scheme): Book 1, Hadith 242