We ate the predawn meal with the Messenger of Allah ﷺ, then we went out to the mosque and the prayer was called. I asked, "How long was the interval between the two?"He replied, "About the time it takes a man to recite fifty verses."
حدثنا يحيى عن هشام حدثنا قتادة عن أنس
تسحرنا مع رسول الله ﷺ فخرجنا إلى المسجد فأقيمت الصلاة قلت كم كان بينهما قال قدر ما يقرأ الرجل خمسين آية
Its isnad is sahih, and its narrators are leading authorities as well. The hadith was also narrated with similar wording by Bukhari 3/37, Muslim 2/771 no. 1097, Tirmidhi 3/75 no. 703, who said, hasan sahih, Nasai 4/143 no. 2155, Ibn Majah 1/540 no. 1694, and Darimi 2/11 no. 1695, all of them in the book on fasting, in the chapter on the merit of the pre-dawn meal, delaying it, and its duration.