عَن أنس بن مَالك
يَقُولَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَنْ يَبْرَحَ النَّاسُ يَتَسَاءَلُونَ حَتَّى يَقُولُوا هَذَا الله خَالق كل شَيْء فَمن خلق الله»
‘God created everything, but who created God?’ “ Bukhari transmitted it. Muslim’s version is: He declared that God said, ‘Your people will continue to ask, ‘What is this?’ and ‘what is that?’ till they propound this: God created all things, but who created God?’”
Mishkat al-Masabih 71, Book 2, Faith, Hadith 70. 1 min read