question #3 Sahih al-Bukhari 7553, Book 97, Hadith 178 : What is the significance of the divine book mentioned in relation to Allah’s mercy and anger?

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.”