Volume 3 · Book 31 · Hadith 144
Narrated Anas: Zaid bin Thabit said, "We took the Suhur with the Prophet . Then he stood for the prayer." I asked, "What was the interval between the Suhur and the Adhan?" He replied, "The interval was sufficient to recite fifty verses of the Quran."
— Sahih Bukhari, Volume 3, Book 31: Fasting, Hadith #144