Sahih Muslim 1491
صحيح مسلم#1491SahihAbd al-Rahman b. Abd 'Amr reported:'Uthman b. 'Affan (narrated the mosque after evening prayer and sat alone. I also sat alone with him, so he said: 0, son of my brother, I heard the Messenger of Allah (ﷺ) say: He who observed the 'Isha' prayer in congregation, it was as if he prayed up to midnight, and he who prayed the morning prayer in congregation, it was as if he prayed the whole night
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: 5:324