Hadith 1:59
Muttafaqun 'alayh (Zubair `Aliza'i)
He also reported God’s messenger as saying, “The devil comes to one of you saying, ‘Who created this? Who created that?’ even saying, ‘Who created your Lord?’ "When he gets that length the man should seek refuge in God and stop thinking about it.” (Bukhari and Muslim.)
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: " يَأْتِي الشَّيْطَانُ أَحَدَكُمْ فَيَقُولُ: مَنْ خلق كَذَا؟ مَنْ خَلَقَ كَذَا؟ حَتَّى يَقُولَ: مَنْ خَلَقَ رَبَّكَ؟ فَإِذَا بَلَغَهُ فَلْيَسْتَعِذْ بِاللَّهِ وَلْيَنْتَهِ "
Original Reference: Mishkat al-Masabih 65