question #1 Sahih Muslim 945f, Book 11, Hadith 71 : What is the significance of verifying the authenticity of a hadith through multiple sources?

He who follows the bier, for him is the reward of one qirat. Ibn ‘Umar said: Abu Huraira narrated it too often. So he sent (a messenger to) ‘A’isha to ascertain (the fact). She (‘A’isha) testified Abu Huraira. Ibn ‘Umar said: We missed so many qirats.