This is part of Jalal Abualrub’s book, Muhammad’s Role in Islam:
Imam Malik Ibn Anas (93-179AH/711-795CE), who collected, Al-Muwattaa, which is a hadeeth collection, was the teacher of Imam Muhammad Ibn Idris Ash-Shafi`i (150-204/767-819), who collected a Musnad, a hadeeth collection that carries his name, Musnad Ash-Shafi`i. Ash-Shafi’i was the teacher of Imam Ahmad Ibn `Hanbal (164-241/780-855), who collected the famous and vast Hadeeth collection simply known as, Al-Musnad.
All three of these Imams were major scholars of Hadeeth, Fiqh (Islamic Law), and other Islamic topics. It should be noted that the word, musnad, shares the same root word as, isnad. A musnad collects narrations reported from the Prophet’s Companions, each Companion separately, by listing all the narrations leading to each Companion separately from the other Companions.
Example of Isnad: Here is a rare hadeeth narration Imam Ahmad Ibn `Hanbal collected in his Musnad, hadeeth number 5597; this hadeeth is also found in, Al-Muwattaa, by Imam Malik [1188].
Ahmad Ibn `Hanbal wrote, “Muhammad Ibn Idris Ash-Shafi’i, may Allah grant him His Mercy, narrated to us saying, ‘Malik [Ibn Anas] reported to us from Nafi` from Abdullah Ibn `Umar, that the Messenger of Allah said, “Do not spoil the sales of others.”
This hadeeth prohibits spoiling business transactions of others, such as by saying to the buyer, “Cancel the deal you [made] with so and so, and I will give you the same product for a cheaper price,” or by saying, “I will give you a better product than the one you are buying from so and so, but for the same price” (Nawawi, Yahya Ibn Sharaf. Shar`h Sahih Muslim).
In the example provided here from, Al-Musnad, Imam Ahmad narrated this hadeeth from Imam Ash-Shafi’i, his teacher in this hadeeth, who narrated the hadeeth from Imam Malik, Ash-Shafi`i’s teacher. Imam Malik reported this hadeeth by mentioning the name of his teacher, Nafi’ [d. 117AH/735], Abdullah Ibn `Umar’s famous student, and Nafi` mentioned the name of his teacher, Abdullah Ibn `Umar, the Prophet’s close Companion, who reported the Prophet’s statement mentioned above. Malik was from the third generation of Islam; only two narrators are between him and the Prophet, Allah’s blessing and mercy on him, in many of the hadeeths he collected.
It should be noted that Imam Malik verbally reported the portion of the hadeeth quoted here using two different chains of narrators, including this one from Nafi`, from Abdullah Ibn `Umar. In addition, other major hadeeth collections, such as Bukhari, Muslim, An-Nasaii [4420], Abu Dawud (2979; 2986), Ahmad’s Musnad [4302; 5597; 8581], and others, also collected the portion of this hadeeth quoted here through Malik, some of them reporting both of Malik’s chains of narrators. Imam Malik himself reported his two different chains of narrators for the portion of the hadeeth under discussion in his famous book, Al-Muwatta [1188; 1189]. (Jalal Abualrub. Muhammad’s Role in Islam, Pg., 89-90)