The Messenger of Allah (ﷺ) used to observe two rak'ahs of Sunnah (prayer) when he heard the Adhin and shortened them.
Sahih Muslim Book 6, Hadith 111
← Previous Hadith When the dawn appeared, the Messenger of Allah (ﷺ) observed two rak'ahs (of Sunnah prayers).

Sahih Muslim Book 6, Hadith 110 Next Hadith → " When it was dawn".

Sahih Muslim Book 6, Hadith 112