Sahih Bukhari
Times of the Prayers
Volume: 001 / Book Number: 010 / Hadith Number: 549
Narrated Anas:
Zaid bin Thabit said, "We took the "Suhur" (the meal taken before dawn while fasting is observed) with the Prophet and then stood up for the (morning) prayer." I asked him how long the interval between the two (Suhur and prayer) was. He replied, 'The interval between the two was just sufficient to recite fifty to Sixth 'Ayat."