This hadith has been narrated on the authority of Anas through another chain of transmitters.
The Book of Zuhd and Softening of Hearts - Sahih Muslim 2991 b
This narration from Anas ibn Malik (may Allah be pleased with him) serves as a corroborating witness (mutaba'ah) to the primary chain of transmission, strengthening the authenticity and reliability of the Prophetic tradition. Such multiple chains are highly valued in the science of hadith as they demonstrate wide acceptance among the Companions and reduce the possibility of error.
The scholars of hadith explain that when a tradition is narrated through different chains (turuq), it elevates the status of the narration and provides greater certainty in its attribution to the Prophet Muhammad (peace be upon him). This principle, known as "ta'kid" (corroboration), is fundamental to verifying the soundness of Prophetic traditions.
Imam Muslim's inclusion of this supporting chain reflects his meticulous methodology in compiling his Sahih, where he sought to present the most authentic traditions with the strongest evidence. The repetition through different transmitters from the same Companion indicates the importance the early community placed on preserving the exact words and teachings of the Messenger of Allah.