Messenger of Allah ﷺ said, "When Allah completed the creation, He wrote in His Book which is with Him on His Throne, "My Mercy overpowers My Anger." (Using translation from Bukhārī 3194)
أَنَّ النَّبِيَّ ﷺ قَالَ «لَمَّا قَضَى اللهُ الْخَلْقَ كَتَبَ فِي كِتَابِهِ فَهُوَ عِنْدَهُ فَوْقَ الْعَرْشِ إِنَّ رَحْمَتِي غَلَبَتْ غَضَبِي» اللَّفْظُ لِقُتَيْبَةَ