Sahih Bukhari
Fasting
Volume: 003 / Book Number: 031 / Hadith Number: 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."