Sunan Abi Dawud 1412
سنن أبي داود#1412SahihNarrated Ibn 'Umar:The Messenger of Allah (ﷺ) would recite to us a surah (according to the version of Ibn Numair) outside the prayer (the agreed version goes), then he would prostrate along with him, and none of us could find a place for his forehead
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari (1075) Sahih Muslim (575)
In-book reference: 7:12