Sahih Muslim 135
Sahih Muslim · Book 1: The Book of Faith · Clarifying the Waswasah (Whispers, Bad Thoughts) with regard to faith, and what the one who experiences that should say
Yazid b. al-Asamm said:
حَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ ، حَدَّثَنَا كَثِيرُ بْنُ هِشَامٍ ، حَدَّثَنَا جَعْفَرُ بْنُ بُرْقَانَ ، حَدَّثَنَا يَزِيدُ بْنُ الأَصَمِّ ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ ، يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لَيَسْأَلَنَّكُمُ النَّاسُ عَنْ كُلِّ شَىْءٍ حَتَّى يَقُولُوا اللَّهُ خَلَقَ كُلَّ شَىْءٍ فَمَنْ خَلَقَهُ " .
I heard Abu Huraira saying that the Messenger of Allah (ﷺ) observed: people will certainly ask you about everything till they will propound: Allah created every thing, but who created Allah?