Bismillahi Al-Rahmani Al-Rahim
As Salaam Alaikum
Can you tell me the position of the book Al-Kafi by shaikh Ibn
Qudhamah [RH] (The full title is "Al-Kafi ..Masail-e-Imaam Ahmad Bin
wa `alaykum al-salam wa rahmatullahi wa barakatuhu
The book in question is the third book in a series of four books that Ibn Qudamah (may Allah be merciful with him) wrote.
The first book in the series is Al-`Umdah, which is for beginners and sticks to the strongest ruling without really providing evidence. Today this book is typically read with the commentary Al-`Uddah, which adds opinions within the madhhab and of other madhabs, evidence [dalil], the significance of the evidence [wajh al-istidlal] and the underlying reason [ta`lil]. The `Uddah is usually read after one has gone through a book like Nail al-ma'arib or Kashf al-mukhaddarat.
The second is Al-Muqni`, adds to this by giving the different opinions within the madhhab without necessarily saying which one is strongest. Al-Hajjawi condensed this into Zad al-mustaqni`, giving only the strongest opinion. Al-Buhuti's Al-Raud al-murbi` is a commentary on this book, and it is a basic text book and source of fatwa for Hanbalis outside of Sham.
The third is Al-Kafi, adds evidence and argumentation. While it is an important work and sometimes is cited, it does not seem near as important as Al-`Umdah or Al-Mughni.
The fourth is Al-Mughni`, which gives the positions and evidence for the mujtahid Imams of Ahl al-Sunnah wa al-Jama` (may Allah be pleased with him). Ibn Qudamah did not just stick to the existent schools, but included the opinions of schools and Imams no longer followed; he even gives his reason for doing so: the barakah. The book is still used by Hanbalis and non-Hanbalis alike, though a common pitfall is assuming that Ibn Qudamah's position is used for fatwa today.
This last point applies to the other books in the series. So while these books are very useful, one thing that they cannot be used for is knowing the position according to the madhhab today; for this you need to go to later books. But they're still plenty useful for other things, especially when it comes to understanding the significance of evidence and seeing how Hanbalis work things out.
And Allah knows best.
wa al-salamu `alaykum