question #3 Sahih Muslim 1060c, Book 12, Hadith 182 : Why is it important to compare different narrations of the same hadith?

This hadith has been narrated by Sa’id with the same chain of transmitters, but no mention has been made of Alqama b. ‘Ulatha, nor of safwin b. Umayya, and he did not mention the verse in his hadith.