Sunan an-Nasa'i 624
سنن النسائي#624SahihIt was narrated from Nafi' bin Jubair, from his father, that the Messenger of Allah (ﷺ) said during a journey:"Who will watch out for dawn for us, so that we do not sleep and miss the dawn prayer?" Bilal said: 'I will.' He turned to face the direction where the sun woke them up, then they got up. He said: 'Perform Wudu'.' Then Bilal called the Adhan and he prayed two Rak'ahs, and they prayed the two (Sunnah) Rak'ahs of Fajr, then they prayed Fajr
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih Isnaad
Al-AlbaniSahih Isnaad
Zubair Ali ZaiIsnaad Sahih
In-book reference: 6:131