Oneness, Uniqueness of Allah (Tawheed) — Hadith #7554

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 is written with Him over the Throne." (see Hadith 3194)

إِنَّ اللَّهَ كَتَبَ كِتَابًا قَبْلَ أَنْ يَخْلُقَ الْخَلْقَ إِنَّ رَحْمَتِي سَبَقَتْ غَضَبِي‏.‏ فَهْوَ مَكْتُوبٌ عِنْدَهُ فَوْقَ الْعَرْشِ ‏"

See also hadith 3194.