What does it mean that an "Aziz" Hadith was narrated by two, and does this refer to Al-Bukhari and Muslim? Also, what is meant by the "narrator" of the Hadith, and what is the difference between an "Aziz" Hadith and a "Sahih" Hadith?

The "Aziz Hadith" is one that has been narrated by two individuals in one of its chain's layers, even if more than two narrated it in other layers. An example of this is the hadith: "None of you believes until I am more beloved to him than his father and his child," for it was narrated only by Anas and Abu Hurairah from the Prophet, peace and blessings be upon him.

The term "hadith narrator" refers to the Companion who narrated the hadith from the Prophet, peace and blessings be upon him, and also to the one who compiled it in his book.

An Aziz hadith can be sound (sahih) or weak (da'if). A sound hadith can be Aziz or otherwise. Thus, Aziz is a term concerned with the number of narrators in one of the chain's layers, whereas soundness depends on the fulfillment of the known conditions of soundness.