What other are the commonly used hadith collections (besides the famous 6 i.e.
Saheeh Muslim, Saheeh Bukhari, Jami'at al-Tirmidhi, Muwatta Malik, Sunan Abi Dawood and Sunan An-Nisai), and what is the relative authenticity of these other sources ?
Asalamu Alaykum brother.
Other than the 6 books of hadeeth in sunni corpus of hadeeth, we have Imam Malik's Muwatta, Imam Ahmeed Bin Hanbal's Musnad, Imam Shafie's Musnad, Imam Khuzayma's Sahih collection, Imam Hibban's Sahih collection, Sunan al-Darimi.
Imam Malik's Muwatta is the first hadeeth collection which was collected for fiqh issues, and it is authentic. Imam Shafie has said concerning it that it is the second most authentic book on the fact of earth. First and totally authentic being the book of Allah i.e Qur'an.
Imam Ahmed's Musnad is question by many scholars of past and present. It contains Rigorously Authentic, Authentic and Weak Hadeeths.
Imam Ibn Hibban's collection is also Sahih, but many scholars of Islam have found that there are many Weak hadeeths in this collection despite the claims of its author that it is 100 authentic.
Imam Ibn Khuzayma's is also Sahih, but many scholars of Islam have found that there are many Weak hadeeths in this collection despite the claims of its author that it is 100 authentic.
Imam Shafie's books can also be considered equal to Musnad of Ahmed
of others, I don;t have adequate knowledge.