The Messenger of Allah ﷺ and Zayd bin Thabit ate the predawn meal, then they got up and entered into the dawn prayer. We asked Anas, "How long was it between their finishing the meal and entering the prayer?"He replied, "About the time it takes a person to recite fifty verses."
أخبرنا أبو الأشعث قال حدثنا خالد قال حدثنا سعيد عن قتادة
تسحر رسول الله ﷺ وزيد بن ثابت ثم قاما فدخلا في صلاة الصبح فقلنا لأنس كم كان بين فراغهما ودخولهما في الصلاة قال قدر ما يقرأ الإنسان خمسين آية
Bukhari reported it in the Book of Prayer Times, chapter on the time of Fajr, no. 576, from the hadith of Saeed bin Abu Aruba, with this chain. It is also found in al-Kubra, no. 2467. See also the two preceding hadiths.