The work is primarily a collection of including ahadith and narrations from the Salaf (early generations).
For the uninitiated, the specific search term may appear cryptic. However, to students of `Aqidah (Islamic creed), this string points directly to one of the most critical chapters in Sahih al-Bukhari (Book 97, Section 39, often referencing Hadith 39 or the 39th point within "Kitab Khalq Af’al al-‘Ibad") and the broader theological treatises surrounding divine decree (Qadr). khalq af 39-al al-ibad english pdf