Ati said, I asked Ibn Umar, "Tell me about the two units of prayer before the dawn prayer. Should I lengthen the recitation in them?"He replied, "The Prophet ﷺ used to pray during the night in pairs, finishing with a single unit as witr, and he would pray the two units before the dawn prayer as though the call to prayer were already in his ears."
سألت ابن عمر؛ قلت: أرأيت الركعتين قبل صلاة الغداة أطيل فيهما القراءة؟ فقال: كان النبي ﷺ يصلي من الليل مثنى مثنى، ويوتر بركعة، ويصلي الركعتين قبل صلاة الغداة. وكأن الأذان بأذنيه.
Bukhari narrated it in the chapter on Witr prayer (995), and Muslim in the chapter on the prayer of travelers (157/749), both from the hadith of Hammad bin Zayd, who said, Anas bin Sirin narrated to us, then he mentioned it. The wording given is Bukhari's, and Muslim's wording, which was mentioned earlier, is close to it with some additions.As for his saying, "as if the adhan were in his ears," Hammad said, meaning quickly.