Sahih Muslim 1018
صحيح مسلم#1018SahihJabir b. Samura reported:'Umar said to Sa'd: They complain against you in every matter, even in prayer. He (Sa'd) said: I prolong (standing) in the first two (rak'ahs) and shorten it in the last two, and I make no negligence in following the prayer of the Messenger of Allah (ﷺ). He ('Umar) remarked: This is what is expected of you, or, that is what I deemed of you
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 4:180