I was wondering about what the scholars of Rijal have said is to be done when a reliable narrator very late in his life narrates a tradition, but it can be proven either by the words of the narrator without doubt, that when they had narrated that their memory had notable defects and that they were very old.
Rather than being a ‘Sahih’ chain, would this invariably cause it in and of itself to drop to a Hasan level, due to memory being the distinguisher between Hasan and Sahih?
For instance, we find that Imam Muslim (rahimahullah) narrates in Sahih Muslim that Zayd ibn Arqam (radiyallahu’anhu) began to narrate a Hadith about Rasulullah (sallallahu’alayhi wasallam) saying he was leaving behind two weighty things. However every chain where he is said to have done this always starts with him first noting down his decline in memory, and that he has grown very old and that his memory has been affected, as he, despite being an upright companion, still was affected by the other causes of old age mortals suffer. We find Imam Bukhari (rahimahullah) does not include this tradition in his Sahih.