Abu Huraira reported:

The Messenger of Allah (ﷺ) said to me: they (the people) till constantly ask you, Abu Huraira, (about different things pertaining to religion) the they would say: Well, there is Allah, but after all who created Allah? He (Abu Huraira) narrated: Once we were in the mosque that some of the Bedouins came there and said: Well, there is Allah, but who created Allah? He (the narrator) said: I took hold of the pebbles in my fist and flung at them and remarked: Stand up, stand up (go away) my friend (the Prophet) told the truth.

وَحَدَّثَنِي عَبْدُ اللَّهِ بْنُ الرُّومِيِّ، حَدَّثَنَا النَّضْرُ بْنُ مُحَمَّدٍ، حَدَّثَنَا عِكْرِمَةُ، - وَهُوَ ابْنُ عَمَّارٍ - حَدَّثَنَا يَحْيَى، حَدَّثَنَا أَبُو سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ لِي رَسُولُ اللَّهِ صلى الله عليه وسلم ‏

‏ لاَ يَزَالُونَ يَسْأَلُونَكَ يَا أَبَا هُرَيْرَةَ حَتَّى يَقُولُوا هَذَا اللَّهُ فَمَنْ خَلَقَ اللَّهَ ‏

‏ قَالَ فَبَيْنَا أَنَا فِي الْمَسْجِدِ إِذْ جَاءَنِي نَاسٌ مِنَ الأَعْرَابِ فَقَالُوا يَا أَبَا هُرَيْرَةَ هَذَا اللَّهُ فَمَنْ خَلَقَ اللَّهَ قَالَ فَأَخَذَ حَصًى بِكَفِّهِ فَرَمَاهُمْ ثُمَّ قَالَ قُومُوا قُومُوا صَدَقَ خَلِيلِي ‏.‏