From Sahih Bukhari (Hadith 1159):
Narrated `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
Reference: Bukhari 1159