Sahih Muslim 1015
صحيح مسلم#1015SahihAbu Sa'id al-Khudri reported:The Apostle of Allah (ﷺ) used to recite in every rak'ah of the first two rak'ahs of the noon prayer about thirty verses and in the last two about fifteen verses or half (of the first rak'ah) and in every rak'ah of the 'Asr prayer of the first two rak'ahs about fifteen verses and in the last two verses half (of the first ones)
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: 4:177