Sunan an-Nasa'i 1771
سنن النسائي#1771SahihIt was narrated from Ibn 'Umar that Hafsah told him:"When he was called to Subh prayer, the Messenger of Allah (ﷺ) would do two prostrations before Subh prayer
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 20:174