Sahih al-Bukhari — Oneness, Uniqueness of Allah (Tawheed) — Hadith No: 7553
وَقَالَ لِي خَلِيفَةُ بْنُ خَيَّاطٍ حَدَّثَنَا مُعْتَمِرٌ، سَمِعْتُ أَبِي، عَنْ قَتَادَةَ، عَنْ أَبِي رَافِعٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " لَمَّا قَضَى اللَّهُ الْخَلْقَ كَتَبَ كِتَابًا عِنْدَهُ غَلَبَتْ ـ أَوْ قَالَ سَبَقَتْ ـ رَحْمَتِي غَضَبِي. فَهْوَ عِنْدَهُ فَوْقَ الْعَرْشِ ".
Translation
Narrated Abu Huraira:I heard Allah's Messenger (ﷺ) saying, "Before Allah created the creations, He wrote a Book (wherein He has written): My Mercy has preceded my Anger." and that (Book) is written with Him over the Throne