After the sad demise of our Holy Prophet Muhammad (Peace be upon him), there was great literature remained among his companions. The need was felt to compile the hadith by the companions of our Holy Prophet Muhammad (Peace be upon him). Then two methodologies were adopted named Musnad and Musnaf. Though both of the methods are related to the compilation of the hadith, both are different in nature from each other.
In the method of Musnad, the hadith is compiled with the name of its narrators and transmitters. The complete details of the narrators were also enclosed in this method. The hadith compiled in this method was indiscriminately and regardless of the content. There are some examples of Musnad are Musnad of Ayesha, Musnad of Abu Bakar and Musnad of Abu Huraira.
Another famous compilation was Musnad e Ahmad which was compiled by Imam Ahmad bin Hambal. Imam Ahmad bin Hambal collected about 75000 hadiths from which he accepted about 30000 and refused the rest of the hadiths. These were regardless of any issue or topic and revolved around the primary sources. Female companions are also listed in Musnad.
As Musnad is regardless of any topic or content of hadiths, the Musnaf contains the hadiths according to the contents and topic. The placement of hadith is content and topic wise in Musnaf. Examples can be considered as Namaz, Zakat, Fasting, Marriage, Hajj, and Jihad, etc.
This compilation is considered a reliable source of knowledge about any topic because it contains details on specific topics. One example of this compilation is Muwatta Imam Malik compiled by Imam Malik which contains about 1720 hadiths in it. There are some other examples of this compilation, Musnaf, which are included in Sahah-e-Sitta named Sahih al Bukhari, Sahi Muslim, Sunan Nisai, Sunan Tirmizi, Ibn Dawud and Ibn Majah.