Jaami’ al ‘Uloom wal Hikkam fee Sharh Khamseen Hadeeth min Jawaami’ al Kalim.
Ibnus Salaah gave a lecture entitled ‘Al ahaadeeth al Kuliyyah’ where he gathered Ahaadeeth that the religion of Islaam revolves around, he mentioned twenty six Ahaadeeth.
Al Imaam an Nawawee took these Ahaadeeth and added more to them until they reached forty two Ahaadeeth, he called his book ‘The Forty’. It became widely known and memorized, and Allaah benefited people through it due to the sincerity of his intention.
Al Haafidh ibn Rajab al Hanbalee added eight more Ahadeeth to them making them fifty. He performed Istikhaarah in response to a request by some students of knowledge to explain these Ahadeeth in this magnificent book.