Sunan an-Nasa'i 476
سنن النسائي#476SahihIt was narrated that Abu Sa'eed Al-Khudri said:"The Messenger of Allah (ﷺ) used to stand in Zuhr and recite the equivalent of thirty verses in each Rak'ah, then in the first two Rak'ahs of 'Asr he would stand for the equivalent of fifteen verses
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
In-book reference: 5:29