question #3 Sahih al-Bukhari 7404, Book 97, Hadith 33 : What is the significance of Allah writing about His mercy in His Book placed on the Throne?

The Prophet (ﷺ) said, “When Allah created the Creation, He wrote in His Book–and He wrote (that) about
Himself, and it is placed with Him on the Throne–‘Verily My Mercy overcomes My Anger.’”