Is every Hadith mentioned in Sahih al-Bukhari and Muslim authentic, and are the narrations attributed to the Companions in these two books authentic to the same degree of authenticity as the narrations of the Messenger of Allah, may Allah bless him and grant him peace?

The scholars have agreed, by and large, upon the authenticity of the narrations with a connected chain of transmission (musnad) in the two Sahih (definition) collections, except for a few isolated instances that some memorizers of hadith (definition) have criticized. As for Al-Bukhari's mu'allaqat (suspended narrations) — which are those he reported as مرفوع (traced back to the Prophet, peace be upon him) without a chain of transmission or by omitting the beginning of its chain — they do not hold the same ruling as the musnad hadiths in terms of acceptance. Among them, some are authentic according to Al-Bukhari's conditions or other conditions, and some are subject to discussion. This also applies to the few mu'allaqat in Sahih Muslim.