The Prophet (ﷺ) used to pray thirteen rak'ahs during the night including the two rak'ahs of the dawn prayer.
Sunan Abi Dawud Book 5, Hadith 111
← Previous Hadith The Messenger of Allah (ﷺ) used to pray thirteen rak'ahs, observing six rak'ahs in pairs including the two rak'ahs of dawn prayer. He would observe witr and five rak'ahs. He sat only in the last of them.

Sunan Abi Dawud Book 5, Hadith 110 Next Hadith → The Messenger of Allah (ﷺ) offered the night prayer and then prayed eight rak'ahs standing, and two rak'ahs between the two adhans (i.e. the adhan for the dawn prayer and the iqamah). He never left them.

Jaf'ar b. Musafir said in his version: (He prayed) the two rak'ahs sitting between the two adhans. He added the word "sitting".

Sunan Abi Dawud Book 5, Hadith 112