I spent the night at the home of my aunt Maymunah. The Prophet ﷺ got up to pray during the night and prayed thirteen rakahs, including the two rakahs of Fajr. I estimated his standing in each rakah to be about the length of "You who is wrapped in garments" [Muzzammil 73:1].Nuh did not include the phrase "including the two rakahs of Fajr."
حدثنا نوح بن حبيب ويحيى بن موسى قالا حدثنا عبد الرزاق أخبرنا معمر عن ابن طاوس عن عكرمة بن خالد
بت عند خالتي ميمونة فقام النبي ﷺ يصلي من الليل فصلى ثلاث عشرة ركعة منها ركعتا الفجر حزرت قيامه في كل ركعة بقدر يا أيها المزمل لم يقل نوح منها ركعتا الفجر
[Its isnad is sahih] Ahmad narrated it, 1/365, from the hadith of Abdul-Razzaq through the same chain, and it is found in his Musannaf, no. 4706, and Nasai narrated it in Al-Kubra, no. 1425.