question #1 Sahih Muslim 929c, Book 11, Hadith 29 : What is the significance of ensuring the completeness and accuracy of a hadith narration?

We were with the bier of Umm Aban, daughter of ‘Uthman, and the rest of the hadith is the same, but he did not narrate it as a marfu’ hadith on the authority of ‘Umar from the Messenger of Allah (ﷺ) as it was narrated by Ayyub and Ibn Juraij, and the hadith narrated by them (Ayyub and Ibn Juraij) is more complete than that of ‘Amr.