Why is "peace be upon him" (sallallahu alayhi wa sallam) mentioned after the names of the prophets and Jibreel in the Hadith of Al-Mi'raj in Sahih Muslim, instead of "upon him be peace" (alayhi as-salam), and is the saying "peace be upon him" (sallallahu alayhi wa sallam) after mentioning Adam and Ibrahim in the Hadith from the narrator's words or from the words of the Prophet (sallallahu alayhi wa sallam)?

We have not come across any statements from scholars clarifying the true nature of the phrase "صلى الله عليه وسلم" (may Allah bless him and grant him peace) in hadith (definition), whether it is an elevated statement [from the Prophet himself] or from the words of the narrators and copyists. Sending blessings upon Prophets and angels is legislated, and its occurrence in some hadiths is usually from the words of the narrators, copyists, or authors.