I asked, "Should I make the two rakahs of fajr lengthy?"He replied, "The Prophet ﷺ used to pray during the night in pairs and would perform witr with a single rakah. He would pray the two rakahs while the call to prayer was still in his ears," meaning he kept them brief.
حدثنا قتيبة حدثنا حماد بن زيد عن أنس بن سيرين قال سألت
أطيل في ركعتي الفجر فقال كان النبي ﷺ يصلي من الليل مثنى مثنى ويوتر بركعة وكان يصلي الركعتين والأذان في أذنه يعني يخفف
Agreed upon (muttafaq alayh). Bukhari transmitted it in Witr, chapter on the hours of Witr, no. 995, and Muslim, no. 749, from the hadith of Hammad bin Zayd, with this wording.On this subject there are also narrations from Ayesha [mentioned earlier, no. 440, 441], Jabir [Ibn Khuzayma, no. 1075, 1261], Fadl bin Abbas [Abu Dawud, no. 1355], Abu Ayub [Abu Dawud, no. 1422], and Ibn Abbas [Muslim, no. 753].