Sahih al-Bukhari 1159
صحيح البخاري#1159SahihNarrated `Aisha;:Allah's Messenger (ﷺ) offered the `Isha' prayer (and then got up at the Tahajjud time) and offered eight rak`at and then offered two rak`at while sitting. He then offered two rak`at in between the Adhan and Iqama (of the Fajr prayer) and he never missed them
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 19:38