Sunan an-Nasa'i 543
سنن النسائي#543SahihJa'far bin Muhammad bin 'Ali bin Al-Husain narrated from his father, that Jabir bin 'Abdullah said:"The Messenger of Allah (ﷺ) prayed Subh as soon as he was certain the dawn had appeared
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 ZaiSahih Muslim
In-book reference: 6:50