Sahih Muslim 1016
صحيح مسلم#1016SahihJabir b. Samura reported:The people of Kufa complained to Umar b. Khattab about Sa'd and they made a mention of his prayer. 'Umar sent for him. He came to him. He ('Umar) told him that the people had found fault with his prayer. He said: I lead them in prayer in accorance with the prayer of the Messenger of Allah (ﷺ). I make no decrease in it. I make them stand for a longer time in the first two (rak'ahs) and shorten it in the last two. Upon this 'Umar remarked: This is what I deemed of thee, O Abu Ishaq
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: 4:178