Book: Ayatul naskh wal mansukh. Narrated by: Abu Abdullah Muhammad ibn Ibrahim an-Nomane. Author: Ali ibn Hussain ibn Musa Sharif al-Murtada Tahqiq: Ali Jihad al-Hasane.
At page 94, in chapter “What was corrupted in Quran” he says:
“As for what was corrupted from the book of Allah, saying: “You are the best of the imams raised up for (the benefit of) men”, and it was changed to “the best of the nations” (1).
And in the footnote we read:
And Ayashi mentioned in his commentary (1/195) : “From Khammad ibn Esa from some of his companions from Abu Abdullah: “In the reading (qiraat) of Ali (this verse in this form) “You are the best of the imams raised up for (the benefit of) men”. (He) said: “That’s family of Muhammad”. And from Abu Baseer: “This verse revealed upon Muhammad (sallalahu alayhi wa ali), about him and successors”, and said: ““You are the best of the imams raised up for (the benefit of) men; you enjoin what is right and forbid the wrong and believe in Allah”, BY ALLAH THIS IS HOW IT WAS REVEALED BY JIBRIL, and it means no one except Muhammad and his successors (salawatullah alayhim ajmayen)